Pratt, J.P.; Roderuck, Charlotte; Coryell, Margaret; Macy, Icie G. (1 November 1946). "Composition of the human placenta: III Vitamin content". American Journal of Obstetrics and Gynecology. 52 (5): 783–787. doi:10.1016/0002-9378(46)90185-8. ISSN0002-9378. PMID20273858.
Pratt, J.P.; Roderuck, Charlotte; Coryell, Margaret; Macy, Icie G. (1 November 1946). "Composition of the human placenta: III Vitamin content". American Journal of Obstetrics and Gynecology. 52 (5): 783–787. doi:10.1016/0002-9378(46)90185-8. ISSN0002-9378. PMID20273858.
Pratt, J.P.; Roderuck, Charlotte; Coryell, Margaret; Macy, Icie G. (1 November 1946). "Composition of the human placenta: III Vitamin content". American Journal of Obstetrics and Gynecology. 52 (5): 783–787. doi:10.1016/0002-9378(46)90185-8. ISSN0002-9378. PMID20273858.
Lim, Robin (2015). Placenta: The Forgotten Chakra (rev. ed.). Bali: Half Angel Press. pp. 122, 128. ISBN978-0-9762907-7-3. OCLC951498666.