1. Postgate JN. Early mesopotamia society and economy at the dawn of history. New York: Routledge; 1992.
2. Perkins R. The history of surrogacy.
http://www.information-on-surrogacy.com/history-of-surrogacy.html
. Accessed 23 July 2011.
3. Society of Assisted Reproductive Technology. Clinic outcome reporting system for gestational carriers, 2004–2009. (E. Nicoll Personal communication). ASRM Public Affairs, SART Registry.
4. Utian WH, Sheean L, Godfarb JM, Kiwi R. Successful pregnancy after in vitro fertilization-embryo transfer from an infertile woman to a surrogate. N Engl J Med. 1985;313:1351–2.
5. Batzofin J, Wilcox J, Nelson J. Gestational surrogacy as an integral part of IVF: a 10 year report. In: Jansen R, Mortimer D, editors. Towards reproductive certainty. Fertility and genetics beyond 1999. New York: The Parthenon Publishing Group; 1999. p. 126–30.