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.
Derby CA, Araujo AB, Johannes CB, Feldman HA, McKinlay JB. Measurement of erectile dysfunction in population-based studies: the use of a single question self-assessment in the Massachusetts Male Aging Study. Int J Impot Res. 2000 Aug 1;12(4):197-204.