1. Aldrovandi, U., 1599-1603. Ornithology, Volume II. Book XIV, pp. 183-352. Translated from the Latin by L. R. Lind 1960. (Manuscript in Kansas State University Library.) Aristotle, G. A., 2, 3 737 a30. See Aldrovandi reference.
2. Versuche über die Partheno-genathische Forschung des Hühnereies;Barfurth;Arch. Entw. Mech.,1896
3. Buffon, G. L. 1771. Hist. Nat. Deseiseaux Im-primerie Royales, Paris.
4. Traite de Physiologie Trad.;Burdach,1838
5. The collection of spermatozoa from the domestic fowl and turkey;Burrow;Poultry Sci.,1937