In addition to using the library search box and/or Google Scholar to identify relevant articles, the following specialized databases are also recommended:
Grey literature is material of a scholarly nature produced outside the usual publication channels such as peer-reviewed journals; it is generally not commercially published (Example).
Strategies to help identify grey literature include:
If you're not familiar with the think tank, IGO, NGO, etc., it's useful to review the About Us section of their website and look for other views about the organization in order to place their work in context and better evaluate the authority and credibility of their work.
Other names for think tanks include policy institutes or research institutes.
A think tank may have an ideological perspective or may be nonpartisan. It's useful to review the About Us section of the think tank's website and look for other views about the think tank in order to place their work in context and better evaluate the authority and credibility of their work.
Note that many think tanks don't take institutional positions on topics but their researchers, scholars, or fellows may take individual, personal positions on policy and other issues, so being aware of the backgrounds of a policy report's author(s) is also helpful.
Examples of think tanks or policy research groups: