Zhao JH, Brunner EJ, Kumari M, Singh-Manoux A, Hawe E, Talmud PJ, Marmot MG, Humphries SE. APOE polymorphism, socioeconomic status and cognitive function in mid-life--the Whitehall II longitudinal study. Soc Psychiatry Psychiatr Epidemiol. 2005;40(7):557-63.
Rothman KJ. Fetal loss, twinning and birth weight after oral-contraceptive use. N Engl J Med. 1977 Sep 1;297(9):468-71.