Fitzpatrick AL, Fried LP, Williamson J, Crowley P, Posey D, Kwong L, Bonk J, Moyer R, Chabot J, Kidoguchi L, Furberg CD, DeKosky ST. Recruitment of the elderly into a pharmacologic prevention trial: the Ginkgo Evaluation of Memory Study experience. Contemp Clin Trials. 2006 Dec; 27(6):541-53.