1. J.O. Almquist, and E.B. Hale , 1956 : An approach to the measurement of sexual behaviour and semen production of dairy bulls. Proc. 3rd Intern. Congr. Animal Reprod., Cambridge, 50 -59 .- (ital.) ref. in: Bonadonna, T., 1949: Das Phantom und einige Hypothesen uber Sexualreflexe der Haustiere Wien. Tierarztl. Wschr. 36, 418.
2. Some aspects of the behaviour of dairy bulls