Risk factors for uterine fibroids: reduced risk associated with oral contraceptives. - Ross,R.K.; Pike,M.C.; Vessey,M.P.; Bull,D.; Yeates,D.; Casagrande,J.T. (Br Med J (Clin Res Ed) 1986; 293: 359 - 362, Erratum in: Br Med J (Clin Res Ed), 1986)