Brubaker L, Richter HE, Barber MD, Hsu Y, Rahn DD, Menefee S, Visco A, Spino C, Martin S, Meikle SF. Pelvic floor disorders clinical trials: participant recruitment and retention. Int Urogynecol J. 2013 Jan 1;24(1):73-9.
Jensen MP, Martin SA, Cheung R. The Meaning of pain relief in a clinical trial. J Pain. 2005 Jun 1;6:400-6.