^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Policastro P, Ovitt CE, Hoshina M, Fukuoka H, Boothby MR, Boime I (Nov 1983). "The beta subunit of human chorionic gonadotropin is encoded by multiple genes". J Biol Chem. 258 (19): 11492–9. PMID6194155.