- Someone affiliated with a reputable organization, university, etc.
- Someone who has authored works that have been characterized or identified as authoritative in the field in question, by multiple reputable sources.
- Someone that has been characterized or identified as an authority in his or her field, by multiple reputable sources.
- Someone who by virtue of their position (in a government agency, for instance) could be considered to be an authority.
No matter where you find a source is listed, check them out. Do your due diligence so that you are not embarrassed later. Run a Google search and a news clip search to look for any controversies, and also see what expert has said about your subject in the past to look for glaring inaccuracies or bias exhibited.
