1. Osathanondh R., Tulchinsky D. Placental polypeptide hormones. In: Tulchinshy D., Ryan K.J. (Eds.), Maternal-fetal endocrinology. Saunders, Philadelphia, 1980, p. 26.
2. Simpson E.R., McDonald P.C. Endocrine physiology on the placenta. Annu. Rev. Physiol. 43:163, 1981.
3. Jaffe R.B. Endocrine physiology of the fetus and fetoplacental unit. In: Yen S.S.C., Jaffe R.B. (Eds.), Reproductive endocrinology. Saunders, Philadelphia, 1986, p. 737.
4. Yen S.S.C. Endocrinology of pregnancy. In: Creasy R.K., Resnik R. (Eds.), Maternal-fetal medicine: principles and practice. Saunders, Philadelphia, 1989, p. 375.
5. Butterworth B.H., Khong T.Y., Loke Y.W., Robertson W.B. Human cytotrophoblast populations studied by monoclonal using single and double biotin-avidin-per-oxidase immunocytochemsttry. J. Histochem. Cytochem. 33:977, 1985.