Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the women's health initiative randomized controlled trial. - Rossouw,J.E.; Anderson,G.L.; Prentice,R.L.; LaCroix,A.Z.; Kooperberg,C.; Stefanick,M.L.; Jackson,R.D.; Beresford,S.A.; Howard,B.V.; Johnson,K.C.; Kotchen,J.M.; Ockene,J. (JAMA, 2002)