Finding grey literature

This is a summary of the first of our information skills workshops in November 2016. Please contact me,, if you have any questions about this topic.


There are lots of different definitions of grey literature, one of the most commonly used is the one given here. It’s an open and vague definition, and depending on how you interpret it could include everything from a government’s statutes, to an email between colleagues, to the TV advert a commercial organisation produces to advertise its products.

According to some definitions, grey literature includes things like websites, tweets and facebook posts, or emails, meeting minutes and other internal business documents. But in this session I’m going to focus on grey literature in what we might consider a more traditional document format – be that an electronic PDF file or a paper document.


Here are some examples of grey literature. This is one of the conservation status reports produced by the New Zealand Department for Conservation. These documents range from just a couple of pages to around 50 pages, depending on the number of taxa. All new documents in this series are catalogued in the Leventis Library catalogue, with a link to the free online PDF. They can also be found easily by online search engines.


The field guide may look similar to published field guides you find in book shops, but this field guide of the Amphibians of Ohio was produced by the Ohio Department of Wildlife, not a commercial publisher. You might find it in specialist libraries, but are unlikely to find it in most library catalogues. It is however available online as a PDF.


This document shows abstracts of Tropical Biology Association (TBA) student project reports. The abstracts can be found on TBA’s website, but only a small number of full reports are currently online. The full reports are, however, available from TBA.


Many student Masters and Doctorate thesis can be found via a straightforward Google search. However, there are better ways of searching for theses if you don’t have a particular reference or the thesis doesn’t appear at the top of your search results. Universities have databases of the theses produced by their students and some will even digitise older theses for you if you request a specific title. There are also amalgamated databases of theses from a geographical or subject area – such as the British Library’s EThOS. For older theses, you may find that you can only access the thesis in hardcopy.


When made available, presentations from conferences, workshops, seminars, etc. can be extremely useful sources of information and are usually available a long time before formally published research results. How useful the PowerPoint documents are without the accompanying presenter will depend on the content of the slides and whether supplementary notes are provided. Conference websites, LinkedIn’s Slideshare and adding filetype:ppt OR filetype:pptx to a Google search are all good sources of presentation documents.


As you can see from the above examples, grey literature can be harder to find than your more traditional library resources – books and journal articles. So, if grey literature is so notoriously hard to find why bother with it?

  • Currency: As it doesn’t have to go through the rigours of a publishers publishing process, grey literature often provides much quicker access to the results of new research.
  • Comprehensive literature reviews: You might be doing work where you need as full a picture as possible about your subject.
  • A source of recent bibliographies: Grey literature can be a good source of recent bibliographies – people put a lot of work into putting reports together, including searching the literature for relevant references. If you’re starting work on a new topic the bibliography / reference list at the end of a report can provide a quick and easy route into finding relevant literature.
  • As a data source: Whether you are looking at huge appendices or just tables within the body of the document, grey literature is often a very good source of data to which you wouldn’t otherwise have access.


So once you’ve decided that it is worth your while looking for grey literature, where do you start? Well that depends very much on what you are looking for. If you are looking for a specific fact or more general information about a topic a Google search can be a good place to start – perhaps with limiters we will discuss in a moment.

For general information on a topic you can also browse the relevant shelves in the Leventis Library – try looking in the boxes but remember that longer reports and hardbound theses will be found with the books. Whether an item goes into the boxes or not depends entirely on its physical properties – i.e. whether it will stand up on the shelf without slipping over. It’s also worthwhile thinking about whether there is an organisation that works on the area you need information on an searching their website for reports or reference lists. For example, AEWA produces a series of reports and species action plans on the conservation of African-Eurasian migratory waterbirds.

If you need a comprehensive overview of a topic, you will need a more structured search strategy. Constructing search strategies is huge topic and there are various approaches you can take. You will need to consider which websites and databases you should search, and what search terms to use. What date range are you interested in? What geographic area? Are you interested in non-English language documents and if so, how will you ensure your sources and search terms reflect this?


If you are using Google (or Google Scholar), you can refine your search in a number of ways. Enclosing your search term in quotation marks will look for documents with your exact phrase. Quotes are also useful for telling Google not to search for words it thinks are related to your search term.

Quotation mark examples:

1. Do you want to know about the Grey parrot, or do you want to know about parrots living in a grey cage?

Grey parrot

Returns results about any parrot which also contain the word grey (although results about grey parrots will usually be at the top of the list).

"Grey parrot"

Only returns results which contain the word grey immediately followed by the word parrot.

2. Do you want Google to guess what you are searching for, or do you want to tell it you know better?

This example is one you probably won’t encounter, but often catches me out when I’m trying to get in contact with colleagues working in other libraries.

Cambridge Librarian

Returns results about lots of libraries in Cambridge.

"Cambridge Librarian"

Returns results about the people who run the libraries!

Another Google trick I’ve already mentioned in association with presentations is the use of the filetype refinement. Add filetype:PDF to your search terms and all the results will be PDF documents, add filetype:doc to your search terms and all the results will be MS Word documents. You can do this with any file type and Google will only return documents in the format you specify. If your search is returning lots of webpages and you want reports try looking for PDFs. If you want presentations look for ppt or pptx documents. Note that you can look for more than one file type at once by separating the terms by or – e.g. filetype:ppt OR filetype:pptx.

My third Google search tip for finding grey literature is specifying a domain to search. Adding will search for government documents, will only search websites ending in so will focus on organisations rather than companies or academic institutions, while will limit your search to university (or similar academic institution) websites. I wouldn’t normally start a search using this refinement, but if your search isn’t returning results which are useful to you, it’s a good one to know.


Finally, there are a few considerations you need to take into account when using grey literature. It’s good practice to think about these things wherever your information is coming from, but it’s even more important when the document has not been through any publishing procedures or checks.

  • Who wrote it? Do you know of them? Do you trust them? What institution do they work/study for? What qualification(s) or subject expertise do they have? Do they have any interests that suggest they might be biased?
  • Why did they write it? Is it intended to inform or persuade? Is it a balanced overview or are they arguing a point? A biased document certainly isn’t useless, but you need to be aware of how you interpret the information contained in it and not allow yourself to be swayed by a good use of language or carefully selected data or statistics.
  • Where did they get the data and can you see it for yourself? Do you trust the data collection methods. Are there any biases in the data which are not mentioned in the text? Where and when is the data from?
  • What do you think of the methodology? How has the data been analysed? Do you agree the method is valid for the situation? What are the assumptions? Are they reasonable?
  • What do you think of their conclusions? Conclusions can be very subjective. What do you think?

Basically, you just need to cast a critical eye over the document. When reading grey literature you need to take the role of reviewer and/or editor as well as reader.


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