Despite their penchant for studying revolutions, historians rarely find themselves in the midst of them; changes of leadership and new administrative structures at universities rarely prove to be as revolutionary as predicted. Yet we are in the midst of a digital revolution that is changing the way we find source material, collect and store our sources, read and interpret them, present and publish them and use them to teach our students. There are few other revolutions in the history of our profession that compare in terms of the implications for how, what and why we research.

The way we access primary source material has changed the environment of archives dramatically. Archives have become photography studios, sites from which sources are copied and removed rather than places to think, work and reflect. The occasional request for a photocopy of a key document has converted into the mass evacuation of whole archives through the lens of a digital camera. Fellow researchers are momentary companions in this process rather than longer term associates sharing coffee and ideas during well-earned breaks. Archivists have become gatekeepers to a digitized and privatized research process carried out mainly in the isolation of the office or the home study rather than in quiet, if sometimes disturbed, contemplation surrounded by other enquiring academics.

Yet this has, on the whole, been a silent revolution. There has been very little in the way of discussion beyond the corridors and common rooms of history departments. Predictably—and fittingly—the more public of these conversations have occurred in online blogs and discussion forums. Now is, perhaps, a good time to reflect in a more consistent and sustained manner on this revolution. That is the objective of this chapter. The focus here is on one researcher’s experience of DIY digitization in the early stages of this revolution, during a collaborative social history project conducted with Professor Henry French (University of Exeter) and Dr Jennifer Jordan between 2007 and 2010. The process of personally accessing, collecting, analysing and interpreting the primary source evidence is my concern here, rather than the use of existing online sources, data storage, the use of meta-data or online publications of sources.

  1. The Project: Man’s Estate

As all DIYers will know—and we’ve all had to do it at some time or another—quite often the best-laid plans do not work out in practice; so it was at times with the Arts and Humanities Research Council project forming the focus of this chapter. The aim, as we conceived of it, was to use a large set of family correspondence to analyse experiences and social constructions of masculine identities within the English landed gentry between the late seventeenth century and the First World War. Existing studies had tended to focus on published conduct literature and court cases, rather than the personal sources we were interested in. Correspondence could potentially provide a window on the way that “men became men” through familial discourse, the role their families played in this process and changes in the social values attached to manliness over this long period of history. The letters existed in abundance in family archives in county record offices and their contents. Everyday though they may have seemed to their creators, they offered valuable insights into the creation of men and manliness across a long period of history. During the majority of our period the gentry remained “the landed gentry”: a useful “control group” that maintained a fairly consistent position in the social hierarchy, as a literate class who incessantly wrote and sent letters to each other.

We had heard from colleagues at Exeter that they had started to use digital photography to collect source material, with good results and there were, as we saw it, several advantages for our project. Firstly, the technique would improve our chances of obtaining the required funding. We factored digital photography into the application to the AHRC from the very beginning, thereby, we argued, saving valuable resources on travel and accommodation, designing a project with good value for money. The AHRC even provided the funds for three state of the art cameras to facilitate this approach along with widescreen laptop computers with which to analyse the letters. Secondly, digitization allowed us to more quickly and efficiently capture large volumes of correspondence and spend more time reading and analysing the letters and less time travelling, booking in, ordering, unfolding and refolding them all. This was particularly beneficial in this type of social history, where generous coverage of period and subject are amongst the main aspirations. Thirdly, capturing and storing the correspondence in this way was particularly suited to collaborative research. We could share the letters electronically—sometimes on an individual basis as we found especially significant passages—ask for second opinions and discuss the meaning of the letters through the documents themselves. Fourthly, the digital capture of the letters allowed us to spend more time with our historical subjects, revisiting them through their correspondence several times as particular aspects of their lives, or particular incidents and periods, became significant through the research process. The benefits seemed clear but the practical implications of the approach were more obscure. DIY digitization on this scale was in its infancy at this time and few other projects had, to our knowledge, made as much use of this technique. In this sense the project was path breaking but we were also navigating uncharted waters, not least in terms of the practicalities of accessing and copying the correspondence in the archives.

  1. The Practicalities: Accessibility and Digitization

Our first task (prior to our application) was to establish where and what we could photograph, as we had no idea which archives would allow DIY digitization given that it was a fairly new research technique. We set about contacting various county record offices where we had identified potentially useful material. The responses varied significantly and many of them raise fundamental issues about digitization that I will consider in the next section. Given that future research projects may well make use of these archives and will depend on goodwill from them I will refrain from identifying these institutions. Some were horrified that we would even contemplate asking such a question. These were “our documents” or “private property” rather than “public property”. How could they know that the documents would not be publicly disseminated? The original donators and relevant living members of the family would never have envisaged such a fate would befall their family archives and allowing them to be digitized would break the bond of trust between donator and archive. More extended discussions surrounded the long-term impact on archives. What would be the point in archives at all if they allowed mass copying of their documents? What impact might this have on footfall over the long term? How could county record offices justify their funding if declining numbers accessed their archives or did so merely to take hundreds of photographs and never reappear?

Other archives were willing to cooperate but were hesitant and cautious about exactly how the process would work and behaved as such once the research began. There were obviously concerns surrounding the preservation of the documents. Would we handle them as carefully as we would if we were reading them in the archives? One county archivist insisted on passing a collection of 120 letters to me individually, booking each letter in and out whilst suspiciously gazing at my every move as I unfolded, read and digitized each letter. I was sat at the closest desk available to the issue desk—five feet away from him—at his request. Although it must have become clear, after a whole morning’s work, that neither of us was having a very enjoyable or profitable time working in this way, the process continued until well into the next day. A number of other archivists were more cooperative but remained cautious, scrutinising us more closely than other visitors and repeatedly asking questions about the nature of the project and checking our credentials, no doubt suspecting that we intended to publish documents without due permissions or acknowledgement. Irritating though these encounters were, these reactions were understandable given that what we were doing was simply not, at that time, what historians generally did in the archives; it was not how one behaved.

Despite these frustrations, the majority of the county record offices we approached were cooperative. Some were even enthusiastic about the project and the approach we were taking. Given how novel the whole situation was, this is a solid testament to the British archive system. In these friendlier environments we were encouraged to order large volumes of correspondence, thereby reducing the time archivists spent collecting the documents and freeing them up to conduct the important business of cataloguing and organising their materials or photocopying documents for other visitors. No eyebrows were raised as we rattled through the collections as long as we did not distract other researchers, some of whom were somewhat surprised, even shocked, at our approach. Three of these archives stand out as particularly inviting. Both the Devon Records Centre and the Wiltshire Record Office had recently been refitted partly in order to facilitate digital photography, with large and well-lit reading rooms. Cambridgeshire Archives were very cooperative. Their staff were familiar with this research technique and delighted that we were using their collections in this way. The majority of these archives also agreed, with the consent of the living members of the subject families, to allow us to publish an edited sourcebook containing a sample of the most interesting letters in the collections.[2] We offered all of these archives digital copies of their correspondence. It was perhaps due the novelty of this technology that only two archives accepted our offer.

For many archivists, digital photography was certainly a ‘dangerous weapon in the researcher’s armoury.’[3] There were, however, other hidden dangers—which seem blindingly obvious now—that we did not foresee until we started to work in this way and had begun to collect large amounts of correspondence. We noted one of these in the book:

Each picture was painless to take and virtually costless. Whole archives succumbed to the camera’s pitiless glare. Within a few months of the start of the AHRC research project, we had amassed approximately 10,000 images, which we now needed to examine. As a consequence there were times in 2008 and 2009, when we feared that we might be buried beneath a mass of correspondence.[4]

In a straightforward practical sense, we were collecting too much material to be able to analyse it fully and effectively. The technology, as tremendously useful as it was, ran ahead of our abilities to transcribe and digest the source material, which was, after all, the core aim of the project. This problem of “time-shifting” in the research process, where less time is spent in the archive but more time is spent analysing the sources in private, is one which many DIY digitizers experience and all of us now understand the need to avoid unmanageably long queues of material.[5] We realized that the technology needed to be used in a way that mapped onto the tried and tested approach that we as historians took to using source material. We needed to stop collecting and start spending far more time reading the letters and we did not compromise in the careful analytical approach we took to reading the letters. We used every archive we had accessed, read every word uttered by our gentry families and we thought carefully about their words and their experiences. We did not use Optical Character Recognition software, the benefits and drawbacks of which are still up for debate, in order to read the letters.[6] After a few weeks we adapted to reading the letters in digital form, making adjustments and refocusing through the digital interface rather than by bodily movements. I managed to get through between fifty and sixty letters each day and was transcribing details from around thirty on a good day. There were, of course, those days when our subjects merely discussed the weather, the state of their health, the cost of tea or the new turnpike road in their neighbourhood, all fascinating for some historian but not for our purposes at the time.

In the main, however, this was a remarkable and very productive experience. Like all good social histories, our project allowed us to get to know our subjects in a very personal way, sharing in their experiences, their trials and tribulations. We uncovered previously hidden experiences that are, we believe, tremendously important for understanding gender and the inculcation of gender in men. It certainly changed the way we think about gender and, we hope, at least gave pause to other historians to reflect on masculinities. Once we had decided on a good balance between collection and analysis we managed to work through around 40000 images, equating to around 15000 letters from nineteen family archives based in ten different county records offices. The transcriptions of these letters were entered into a database, which allowed us to review the transcriptions but also generate quantitative data from the collection. We published two books from the project, one major journal article and several conference papers. The volume of materials we collected and analysed, the coverage we managed to achieve and the timeframe within which we conducted this project (three years) were all facilitated by the use of digital photography and digital software. Given the success of the project and our experiences it seems pertinent to consider the wider implications of this research approach and of digitization more generally for the study of history and for historical archives.

III. The Implications: Social History, Historical Evidence and the Ownership of History

Whether the reactions of archivists were positive (as most were) or negative, the process of establishing potential archives in which to use digital photography certainly enlivened us to some fundamental issues at stake in the new digital world of historical research. I will begin this section by thinking about archives and the “ownership of history”. The tensions with archives that we encountered as we modelled our project have always been present, but were merely brought into sharper relief by this new research technique. The fulcrum of the problems we encountered with some archives rested on issues of accessibility and ownership. All archivists see—or should see—their principal duty to be the preservation of the documents in their care. These documents are the fabric of historical research, they are the stuff of history and must be preserved carefully. Beyond this principle, however, all kinds of things are up for negotiation. Perspectives on this negotiation are telling with regard to the wider issues I have discussed. What should these documents be used for? Should their main purpose be for an intellectual understanding of the past, as historians would argue, or should they merely be preserved as records of the past, as many archivists we encountered seemed to think? Who should have “ownership” of these documents and what should that “ownership” entail? In essence: whose history is it we are researching and who are the stakeholders in that process?

Charging for DIY digital photography in archives is revealing of the perception of archivists that the documents are their possessions and that visitors should pay if they want to “remove” them or “acquire” them from the archive, something that has generated significant debate since digital photography became more common.[7] There is no additional labour required on the part of archivists other than the usual one of locating and delivering the documents to the researcher and, in truth, these charges are applied to make up for shortfalls in public spending. The documents are, of course, in their care and the sources we used were given to them—or loaned to them—by the respective families we studied. But most archives are maintained by public funds, paid at least in part by the taxpayer. Equally, many of the documents contain information that is for public benefit or in the public interest and this principle applies beyond state documentation in the National Archives. Letters from a young gentry man in India, for instance, can reveal important insights into masculine gender norms and, therefore, the history and sociology of gender, a pressing issue in contemporary society. There should, therefore, be a “public interest” in analysing those sources and in having them in the public domain, albeit with due caution in terms of personal privacy and copyright. Gender is “our history” and if we can use personal sources to analyse it then surely we should have the right to do so. The fact that their creators and their families never envisaged these documents being used in this way makes them all the more valuable for historians. Indeed, the various decisions taken by local and central government to accept the archives of landed families (something not envisaged originally in the 1889 legislation) were framed by the perception that these documents were in the public interest. There have even been numerous cases in which deposits have been accepted “in lieu of inheritance tax”, precisely because they are seen as a “national asset”.[8] Issues of ownership are, therefore, more complex and intricate than archivists generally assume.

For historians there are also more colloquial concerns to be considered. The significance attached to primary sources as documents telling us the observations, thoughts, feelings and experiences of people—and therefore as conduits through which to understand the past in its own terms—originates in the German school of history, with Leopold Von Ranke in the nineteenth century. Before this, “second-hand” histories and chronicles were more commonly the stuff of historical literature. These innovations were key to the development of history as a separate and specialized discipline, distinct from subjects such as philosophy and politics.[9] As a consequence we have all been trained, quite rightly, to worship the primary source, the value and uniqueness of each source and the careful way in which sources should be handled, both physically and intellectually. DIY digitization may undermine this process in a number of ways. Mass copying of sources, some may argue, distances the researcher from the source, devalues the individuality and significance of each document both as a material object and as a source of enquiry, thereby distorting the research process.

I would argue that DIY digitization, as opposed to working with digital sources presented online or collected together by others, circumvents some of these problems.[10] In the DIY process the researcher sees and touches the sources themselves and has the kind of personal and sensory connection to the sources and—more importantly—their creators which historians experience in a more traditional process of research. Projects using the digitization technique should, as in our case, allow time for the researcher to read and begin the analysis of samples of the documents in the archive before they are digitally captured. Each detail of the document, marginalia and the finer details of corrections, symbols and doodles can be captured if a careful approach is taken. These are details that libraries and archives sometimes decide to ignore in their own digitization projects.[11] In my experience, the memory of the documents feeds through to a complex connection with the sources, both digital and analogue, once those sources were being analysed on a computer screen. Far from distancing the researcher from the source, the ability to open the document on a computer screen at will allows for a continuing and evolving relationship with it. The documents, particularly the most valuable ones, become still more valuable, more significant as individual sources, more precious. Shield your ears, archivists: the sense that the document is “ours”, is owned, albeit in digital form, makes that connection and individuality all the more significant. This is particularly the case for social and cultural historians who strive to make such personal connections with their subjects in order to “get inside their minds” and see the world from their perspectives.

Interestingly, in my institution students have recently expressed a growing eagerness to examine “real documents” in the archives for their dissertation projects and there has been a growth in the number of students visiting the archives. Colleagues in other institutions have reported similar trends.[12] Far from devaluing the original sources, working in a digital world in which encounters with the past are more likely to be through a digital medium has increased the value of and fascination with “real” documents and source materials. My advice to my students is that, if necessary, feasible and appropriate, students should digitize their sources, thereby saving time and precious resources. But I instruct them to take the same approach we did on our project; to spend time with the sources before copying them and to take the usual due care and attention they would when handling original documents.

Care needs to be taken in analysing and interpreting the documents as digital images. The reproduction needs to be of a good quality and all the usual safeguards need to be applied. E. H. Carr, in his classic examination of the discipline of history (a bible for several generations of undergraduate historians), warned against what he called a ‘commonsense [sic] view of history.’ In this version of historical practice:

History consists of a corpus of ascertained facts. The facts are available to the historian in documents, inscriptions and so on, like fish on the fishmonger’s slab. The historian collects them, takes them home, and cooks and serves them in whatever style appeals to him.[13]

The process of collecting documents now moves at lightning speed compared to Carr’s day but his warnings, that historians should be alive to their own selection and interpretation of “facts” and be self-aware and conscious of their own part in the production of history, are as true today for the DIY digitizer as they were for him. Several additional problems emerge for the DIY digitizer. If archives that do not allow digitization are ignored, then the process becomes one of “digital self- selection”. If individual documents are ignored because they are too difficult to copy, the problem is exacerbated. This issue is also a pressing one on a larger scale for those who use online digital archives. Either as a result of resource issues or through their own misguided selection criteria, some archives have digitized small fractions of larger collections, potentially resulting in “taster menus” for their clients that serve to limit the coverage of research, particularly the more obscure histories that often yield the most interesting results.[14]

In a media-driven world in which we increasingly engage with that world and search for “facts” through electronic devices and screens, perhaps the display of historical documents through this medium may deaden the self-awareness that Carr, Evans and others inculcated in us. During the project we were, as I’m sure most historians are, very aware that we were one step removed from the sources and that we and our worldviews influenced our interpretation. We focused consciously on treating them and thinking about them as carefully as we would physical documents and on reflecting on our own impact on our findings. We relied on our professional training as historians and drove the project through the same analytical skills we applied to any other type of project. The project was driven by our experience as historical practitioners and our knowledge of history and, at the level of analysis as opposed to organization, was assisted but not defined by cameras and computers. As Richard Evans notes:

Whatever the means they use, historians still have to engage in the basic Rankean spadework of investigating the provenance of documents, of enquiring about the motives of those who wrote them, the circumstances in which they were written, and the ways in which they relate to other documents on the same subject.[15]

Concluding Thoughts on Digital History

By way of a conclusion, it is worth reflecting on the place of DIY digitization in the wider vista of digital history. DIY digitization is, after all, only one small part of that larger environment. Historians now research using digital methods but they also communicate in this way. The soundbite discussions on Twitter reporting a conference paper, discussing a source or a reading, or discussing politics, has compressed the space-time of the academic community.  This mode of discourse allows for more frequent conversations which are accessible not only to professional historians but anyone with the time and interest to engage in them. Some of these are whimsical some are more meaningful and productive. Some, such as The Institute of Historical Research’s Digital History account, feed reflective conversations on digitization producing on-going discussion of the uses of this technology as well as live streams or recordings of seminar papers.[16] A recent stream (at the time of writing this essay) focussed on Ryan Cordell’s paper on Scientific America and the discovery of this publication through digital research, a discovery that would have been unlikely without the technology.

Digitization is a modern method of enquiry and analysis fit for the contemporary world of research and like all new technologies—the origins of the written word and print technologies, for instance—it is deeply rooted in the societies that produced it, crafted to answer questions and challenges evolving from that world. Modern historians have a lot to do. Due to increases in rates of literacy and the expansion of the state, particularly from the nineteenth century onwards, primary sources have become increasingly abundant and understanding this complex tapestry of written history has subsequently become evermore challenging. Even historians of earlier periods are stretched. The correspondence we consulted was merely a small fraction of the correspondence available in the archives. More diverse forms of source material have entered the historian’s field of vision as the discipline has expanded beyond its origins in biography, diplomacy and politics to consider society, economics and culture in a far wider sense. In the context of the pressures of REF and the demand for greater value for money in funded research projects, the increase in the pace of historical research and in outputs arising from that research seem all the more necessary. Digital photography, therefore, seems to be an answer to many of the questions facing academics at this point in history. Digitization also answers some more visceral concerns. The digitization of history in war-torn areas of the world such as Iraq will, hopefully, allow those histories to be preserved in the face of cultural and political threats from ideologies opposed to their very existence.

Writing this chapter has drawn me further than I generally venture into the digital world of history and caused me to reflect more deeply on my experiences of using these techniques. This is a world far removed from the very stimulating and exciting academic environment I was introduced to as a young undergraduate at the University of Exeter in 1997. Pigeon-holes, hard-copy journals and green screen library computer catalogues were the order of the day and it was not until my second year that email was even used as the main form of communication (no doubt many academics now wish it had never been invented). Research took place in the local county records office—which in my case was Devon—and cameras were for the professional photographer, remotely commissioned by a wealthy interloper in the world of hard-graft academics, pouring over documents for weeks and months at a time, striking friendships with fellow researchers merely out of the common experience of getting our hands dirty doing “coal-face” research. The change, as always in history, has brought mixed rewards. On the one hand it has been liberating, democratising, exciting and empowering but on the other hand it has led to different types of isolation in the research process and a different kind of academic community.

It has been very exciting to be involved in all these new developments from an early stage as a member of a profession not given to radical change but there are key issues still to be debated and key decisions still to be made. A recent post in the IHR Digital History Twitter feed asked followers to decide on a new avatar for the account. Should it be a) an image of Charles Babbage’s Difference Engine or b) a composite digital image of newsprint?[18] This seems to encapsulate the decisions that we all need to make as historians: whether the technology or the source material should define us. I still cherish the times when I can sit at my desk with a notebook, read an “analogue” book, take notes with a pen, which I still sometimes do. I’m not part of the camp that considers analogue books a thing of the past. Neither would I turn my back on a personal physical connection with the sources. The excitement of finding a document in an archive and handling that document, inhabiting a space that my historical subjects inhabited remains, for me, the greatest pleasure a historian can experience. I see no conflict of interest between this pursuit and the recording of these documents through a digital lens, or some of the wider forms of digital history, providing scholarly good practice remains firmly in place.



Balk, Hildelies, and Lieke Ploeger, ‘IMPACT: working together to address the challenges involving mass digitization of historical printed text’, OCLC Systems & Services: International digital library perspectives, 25.4, 233-248.

Beckett, John, Writing Local History (Manchester: Manchester University Press, 2007).

Carr, Edward Hallett, What is History? (London: Macmillan, 1961), p. 9.

Cohen, Daniel J., and Roy Rozenzweig, Digital History: A Guide to Gathering, Preserving, and Presenting the Past on the Web (Philadelphia, PA: University of Pennsylvania Press, 2006); available at [last accessed 09/08/2016].

Craft, Anna R., and Kathelene McCarthy Smith, ‘Uncovering Social History: An Interdepartmental Approach to Scrapbook Digitization’, The American Archivist, 79.1 (2016), 186-200.

Darby, Nell, ‘The cost of historical research: why archives need to move with the times’, The Guardian Higher Education Network Blog (23 May 2013); available at [last accessed 09/08/2016].

Evans, Richard J., In Defence of History (London: Granta, 2000), pp. 16-23.

French, Henry F., and Mark Rothery, Man’s Estate: Landed Gentry Masculinities 1660-1900 (Oxford: Oxford University Press, 2012).

Hafner, Katie, ‘History, Digitized (and Abridged)’, The New York Times (10 March 2007); available at [09/08/2016].

Hitchcock, Tim, ‘Confronting the digital: or how academic history writing lost the plot’ Cultural and Social History, 10.1 (2013), 9-23.

Rothery, and Henry French, eds, Making Men: The Formation of Elite Male Identities in England, c.1660-1900; A Sourcebook (Basingstoke: Palgrave Macmillan, 2012).

Takats, Sean, ‘Time Shifting and Historical Research’, Blog; available at [last accessed 09/08/2016].


[1] Arts and Humanities Research Council Standard Research Grant Project AH/E007791/1: ‘Man’s Estate: Masculinity and Landed Gentility in England, 1660-c.1918’ (2007-2010). This was preceded by Small Research Grant funded by the British Academy: SG-46123: ‘Practices of Politeness: Changing Norms of Masculinity in Landed Society, 1660-1800’ (2007).

[2] Mark Rothery, and Henry French, eds, Making Men: The Formation of Elite Male Identities in England, c.1660-1900; A Sourcebook (Basingstoke: Palgrave Macmillan, 2012).

[3] Henry F. French, and Mark Rothery, Man’s Estate: Landed Gentry Masculinities 1660-1900 (Oxford: Oxford University Press, 2012), acknowledgements.

[4] Ibid.

[5] See Sean Takats, ‘Time Shifting and Historical Research’, Blog; available at [last accessed 09/08/2016].

[6] Hildelies Balk, and Lieke Ploeger, ‘IMPACT: working together to address the challenges involving mass digitization of historical printed text’, OCLC Systems & Services: International digital library perspectives, 25.4, 233-248.

[7] See, for example, Nell Darby, ‘The cost of historical research: why archives need to move with the times’, The Guardian Higher Education Network Blog (23 May 2013); available at [last accessed 09/08/2016].

[8] John Beckett, Writing Local History (Manchester: Manchester University Press, 2007), p. 169.

[9] For a useful summary on the impact of Leopold Von Ranke’s innovations, see Richard J. Evans, In Defence of History (London: Granta, 2000), pp. 16-23.

[10] For a useful survey of some of the problems involved in different forms of digital research see Tim Hitchcock, ‘Confronting the digital: or how academic history writing lost the plot’ Cultural and Social History, 10.1 (2013), 9-23.

[11] Daniel J. Cohen, and Roy Rozenzweig, Digital History: A Guide to Gathering, Preserving, and Presenting the Past on the Web (Philadelphia, PA: University of Pennsylvania Press, 2006); available at [last accessed 09/08/2016]. Some projects, however, are specifically focused on the “ephemera” of history, for example Anna R. Craft, and Kathelene McCarthy Smith, ‘Uncovering Social History: An Interdepartmental Approach to Scrapbook Digitization’, The American Archivist, 79.1 (2016), 186-200.

[12] My co-conspirator in the ‘Man’s Estate’ project, Professor Henry French, has noticed similar developments at the University of Exeter.

[13] Edward Hallett Carr. What is History? (London: Macmillan, 1961), p. 9.

[14] See for example Katie Hafner, ‘History, Digitized (and Abridged)’, The New York Times (10 March 2007); available at [09/08/2016].

[15] Evans, In Defence of History, p. 19.

[16] Available at [last accessed 09/08/2016].


[18] Available at [last accessed 09/08/2016].