Schildkraut JM, Calingaert B, Marchbanks PA, Moorman PG, Rodriguez GC. The impact of progestin and estrogen potency in oral contraceptives on ovarian cancer risk. J Natl Cancer Inst. 2002 Jan 2;94(1):32-8.
Rothman KJ, MacMahon B, Lin TM, Lowe CR, Mirra AP, Ravnihar B, Salber EJ, Trichopoulos D, Yuasa S. Maternal age and birth rank of women with breast cancer. J Natl Cancer Inst. 1980 Oct;65(4):719-22.