1. Almquist , J. O. Hale , E. B. 1956 “An Approach to the measurement of sexual behaviour and semen production of Dairy Bulls” Proc. 3rd. Intern. Congr. Physiol, and Path. Animal Reproduction and Artificial Insemination Plenary Papers Cambridge 50
2. “Sperm Production and Fertility of Dairy Bulls at High-Collection Frequencies with varying Degrees of Sexual Preparation.”;Almquist;J. Dairy Sci.,1958
3. Ariens , A. Th. Bolhuis , E. Spruyt , J. Stegenga , Th. 1954 “Verdere Ontwikkeling van de K. I. in Amerika.” Rapport Studiegroep Veeteelt van de contactgroep Opvoering Productivitcit
4. Baker , F. N. 1954 As quoted by Van Demark N. L., 1956: “Quantitative Aspects of Semen Production in Bulls.” Proc. 3rd. Intern. Congr. Physiol, and Pathol. Animal Reproduction and Artificial Insemination Plenary Papers Cambridge 80
5. “Sexual Functions of Bulls in relation to Heredity, Rearing Intensity and Somatic Conditions.”;Bane;Acta Agr. Scand.,1954