Tulandi T, Martin J, Al-Fadhli R, et al. (junio de 2006). «Congenital malformations among 911 newborns conceived after infertility treatment with letrozole or clomiphene citrate». Fertility and Sterility85 (6): 1761-5. PMID16650422. doi:10.1016/j.fertnstert.2006.03.014.
Simpson ER (2003). «Sources of estrogen and their importance». The Journal of Steroid Biochemistry and Molecular Biology86 (3–5): 225-30. PMID14623515. doi:10.1016/S0960-0760(03)00360-1.
Tulandi T, Martin J, Al-Fadhli R, et al. (junio de 2006). «Congenital malformations among 911 newborns conceived after infertility treatment with letrozole or clomiphene citrate». Fertility and Sterility85 (6): 1761-5. PMID16650422. doi:10.1016/j.fertnstert.2006.03.014.
Simpson ER (2003). «Sources of estrogen and their importance». The Journal of Steroid Biochemistry and Molecular Biology86 (3–5): 225-30. PMID14623515. doi:10.1016/S0960-0760(03)00360-1.