De Angelis C, Drazen JM, Frizelle FA, Haug C, Hoey J, Horton R, et al. Clinical trial registration: a statement from the International Committee of Medical Journal Editors [International Committee of Medical Journal Editors Web site]. May 2005. Available at:
http://www.icmje.org/clin_trialup.htm. Accessed September 15, 2006.