An article by Gina Kolata in the January 17, 2011 New York Times discusses how many randomized controlled trials are lax in their citation of previous studies and describes some of the problems this can cause. Those involved in studies and researching them might want to take a look:
Trial in a Vacuum: Study of Studies Shows Few Citations
The full study is available through EBSCO's Academic Search Complete database, available through Library Services:
Robinson, K. A., & Goodman, S. N. (2011). A Systematic Examination of the Citation of Prior Research in Reports of Randomized, Controlled Trials. Annals of Internal Medicine, 154(1), 50-W19. Retrieved from EBSCOhost.