When I read this statement, I wonder: (1) Does the literature really show this? (2) Can the author prove it in an unbiased way? And (3) how robust is the “proof” (ie, how many published articles back up this statement)? Granted, some things are accepted at face value in science (eg, DNA and gravity), but for other statements, particularly ones that are favorable to an author's or drug sponsor's work, it is useful to back up the claims with valid literature references. I have discussed references in a previous article1 and will not repeat caveats on references, except to emphasize that comments concerning, for example, meeting abstracts, posters, and publications in languages one does not read are relevant to literature searches.