K. J. Betteridge (1981). «An historical look at embryo transfer»(PDF). Reproduction. The Journal of the Society for Reproduction and Fertility. 62: 1–13. Arkivert fra originalen(PDF) 24. september 2015. Besøkt 1. februar 2016. «Three years later, the Estonian, Karl Ernst von Baer, finally found the true mammalian egg in a pet dog (von Baer, 1827).»
snaccooperative.org
Social Networks and Archival Context, SNAC Ark-ID w6zp80vn, besøkt 9. oktober 2017[Hentet fra Wikidata]
web.archive.org
K. J. Betteridge (1981). «An historical look at embryo transfer»(PDF). Reproduction. The Journal of the Society for Reproduction and Fertility. 62: 1–13. Arkivert fra originalen(PDF) 24. september 2015. Besøkt 1. februar 2016. «Three years later, the Estonian, Karl Ernst von Baer, finally found the true mammalian egg in a pet dog (von Baer, 1827).»
