In some disciplines, it may be necessary to look beyond the scholarly articles in that field and also consider grey literature. Grey literature includes conference proceedings and reports produced by government agencies, research institutes or other organizations that are disseminated outside of traditional publication outlets, usually for a professional audience.
Now that more of the grey literature is being made available online, effective Internet searches are particularly important. In the Literature Review Toolbox section of this guide, you'll find a summary of web content management tools that can be instrumental helping you manage and organize the grey literature and other Internet resources.
Reviewing the literature. (2014). In Paulus, T. M., Lester, J. N. & Dempster, P. G. Digital tools for qualitative research (pp. 48-68). London: SAGE Publications Ltd. doi: 10.4135/9781473957671
When it comes to accessing grey literature via Google, there are a couple of steps you can take to help you refine the process. Most of the grey literature available on the Web is in the form of PDF documents. Also consider restricting your search to the .org and/or .gov domains:
AACDOS - A useful tool for evaluating grey literature materials.
Authority - Is the author credible?
Accuracy - Is it supported by documented and authoritative references? Is there a clearly stated methodology? Is it in line with other work on the same topic
Coverage - Have limitations been imposed and are these stated clearly?
Objectivity - Can bias be detected?
Date - Can't find the date? Rule of the thumb is to avoid such material
Significance - Is it relevant? Would it enrich or have an impact on your research?
AACDOS has been developed by Jess Tyndall, Flinders University (access the full document here).