Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.

Grey Literature and Other Sources: Web searching

An overview of key search strategies to locate grey literature, informal or unpublished material. Provides sources and instructions on reporting requirements for systematic reviews.

Web searching title banner

Web searching tips

Google and Google Scholar search tips

  • Unlike databases, basic search boxes usually work better than advanced search options
  • Try starting with broad, simple searches and building on this to focus further as needed
  • Try multiple individual searches with variations of your terms rather than creating one complex search
  • An algorithm underpins the search and usual database search syntax (e.g. OR)  may behave unexpectedly
  • Case and punctuation are generally ignored by Google
  • There is no option to specify truncation. Some alternatives (plurals, alternative spellings, synonyms) are found automatically; others need to be entered in full
  • Result numbers listed in Google can be misleading. Click through to the last page of results for a more accurate count
Tips Examples
Use double quotes to find exactly what you enter. This can be used for phrases, to find two or more terms in that order. "staff ratio"
You can use OR to find alternative terms (must be in capitals) but performance may be unpredictable. Google Scholar has a character limit (256) - you can use a vertical bar instead of OR to save space

"staff ratio" OR "staff to patient ratio"

Alternative option for Google Scholar
"staff ratio"|"staff to patient ratio"

You can use AND to connect different concepts (must be in capitals) but performance may be unpredictable ("staff ratio" OR "staff to patient ratio") AND "aged care"
Group sets of synonyms together. You can use parentheses but Google and Google Scholar will ignore them ("staff ratio" OR "staff to patient ratio") AND ("aged care" OR "nursing homes")
Use AROUND when you are interested in the relationship between two query terms - as a 'proximity' operator. The AROUND(n) operator must be in capitals. staff AROUND(2) ratio finds staffing ratio, staff-to-resident ratio and more
Use the wildcard * as a placeholder for any unknown or wildcard terms. Replaces 1-4 words or numbers.

staff * ratio

staffing * levels

Google and other search engines personalise results depending on your search history, preferences, and websites visited. This is the default setting in Google.

According to the documentation Google released at the time of launch, Verbatim mode disables personalised search and uses your exact words, but will not auto correct spelling or find synonyms. It does not disable localised search which recognises your physical location. Based on this release information, you could use use Verbatim mode when you do not want your search to be invisibly altered. Now, Google help simply states 'Verbatim: Search for exact words or phrases'.

Run your search then select:  Search tools > All results > Verbatim

Image source: Google

Is Google Scholar grey? Google Scholar refers to grey literature in the broad sense of information found outside the recognised databases. It primarily searches academic papers so results are not necessarily grey literature. Results can include:

  • journal and conference papers
  • theses and dissertations
  • academic books
  • pre-prints
  • abstracts
  • technical reports
  • patents; and
  • court opinions

Works are from academic publishers, professional societies and university repositories, as well as scholarly articles available anywhere across the web. Many government documents are indexed from the publisher site not the government site.

In Google Scholar, you may export references one by one by selecting Google Scholar 'Cite' con  and choosing your reference management software (e.g. EndNote).

However, if you wish to export multiple references, there is a more efficient way:

  • log in to your Google account
  • In Google Scholar settings, change Results per page to 20 results per page (maximum allowed)Google Scholar example search with hamburger menu highlighted
  • Select the star to add all your references one by one, page by page to My library
    Example of selecting the Google Scholar 'Save' icon (a star)

  • go to My library
  • select each page of results via the top box (select all)
    Menu items available from 'My Library'
  • export the 20 results (choose your reference management software)
    Export menu available from 'My Library'
  • repeat for all pages

Searching beyond Google: multi-site search, portals, catalogues, 'deep web' searching and more


Search engines such as Google only search a small percentage of the web. Further information is hidden in the 'deep' ('invisible') web and not discoverable by search engine web crawlers. This includes password-protected sites and those not configured for inclusion by Google.

'Federated' (multi-site) search tools are designed to search multiple sources of information simultaneously in real-time, locating material regular search engines don't include. However it may be best to search sources individually to take full advantage of search functionality. 

When searching for grey literature, find more by exploring specialised databases, catalogues, directories, portals and 'federated' search tools. A few of these are listed below:

Guidelines and standards

'If websites, search engines, or other online sources were browsed or searched, specify the name and URL (uniform resource locator) of each source.' - PRISMA 2020 Explanation and Elaboration, p. 5

'Present the full search strategies for all databases, registers, and websites, including any filters and limits used... Provide...the sequence of terms that were used to search simpler interfaces, such as search engines or websites.' - PRISMA 2020 Explanation and Elaboration, p. 7

LibKey Nomad

LibKey Nomad Logo

Use LibKey Nomad™ to easily find full text articles on the internet. Download the free Google Chrome extension to enable direct links to UniSA licensed PDFs on any webpage.

  • Open Chrome
  • Click here or visit the Chrome Web Store and search for "LibKey Nomad" to view the extension details
  • Click the "Add to Chrome" button and confirm when prompted to install the extension:
    Add Nomad to Chrome
  • In the next screen you will be prompted to activate LibKey Nomad™. Start by searching for "University of South Australia" in the Select Institution box:
    Search for institution
  • LibKey Nomad™ will then confirm you have successfully chosen your institution:
    Institution confirmed
  • With the Nomad extension activated in Chrome you will see direct links to relevant articles and PDFs load in real-time on websites such as Wikipedia with the following icon:
    Nomad download PDF
  • Click the icon link and login with your UniSA credentials if asked. You will then have access to the content you’ve requested!

Here is an example of what you expect to see on webpages such as Wikipedia:

example of wikipedia


Advice from the Cochrane Handbook:

'It is particularly important to save locally or file print copies of any information found on the internet, such as information about ongoing and/or unpublished trials, as this information may no longer be accessible at the time the review is written. Local copies should be stored in a structured way to allow retrieval when needed...document the search process to ensure that the methods used can be transparently reported..." -- 4.5 Documenting and reporting the search process