1. Sadleir RMFS. Cycles and seasons. In: Austin CR, Short RV, editors. Reproduction in mammals. I: germ cells and fertilization. New York: Cambridge University Press; 1972. p. 85–102.
2. Induced ovulation in mammals;Milligan;Oxford Rev. Reprod. Biol.,1982
3. Wimsatt WA. Delayed implantation in the ursidae, with particular reference to the black bear (Ursus americanus Pallas). In: Enders AC, editor. Delayed implantation. Chicago: University Chicago Press; 1963. p. 49–76.
4. Bears as induced ovulators—a preliminary study;Boone;Ursus,1998
5. Endocrine and electrophoretic profiles during pregnancy and nonpregnancy in captive female black bears;Hellgren;Can. J. Zool.,1990