What documentation does the author provide?
If the information is presented as fact, does the author document sources?
Documentation means that the author lets you know what sources he or she used to write the information. Documentation is also your key to the evidence the author uses to support his or her statements.
Does the author include citations, footnotes, a bibliography?
The list of sources might also be called Notes, References, Sources, Works Cited, or something similar. Here's an example: