1. Blom, E.; Birch-Andersen, A. 1962. Ultra structure of the stererilizing “knobbed sperm” defect in the bull. Nature. 194: 989–990.
2. Carrol, E.J.; Ball, L.; Scott, J.A. 1963. Breeding soundness in bulls – A summary of 10.940 examinations. Journal American Veterinary Medical Association. 15: 1105–1111.
3. Del Rei, A.J., Bartolomeu, C. C.; Silva, R.C. 2004. Effect of spermatic motility and speed on the semen fertility of bulls. In: International Congress Artificial Reproduction, Porto Seguro, BA, Brazil. 1: 121.
4. Dimitropoulos, E., 1967 La signification du test de la thermo résistance dans l’appreciation de la valeur fécondante du sperme congelé. Annales de Médecine Vetérinaire 4: 215–224.
5. Elliott, F.I. 1976. Techniques for evaluation of bovine semen. Proceedings 6thTechnique Conference On Artificial Insemination And Reproduction. 94–95.