1. Cavestany, D., Galina, C. S. and Cinoles Vinoles, C., 2001. Effect of the characteristics of the postpartum onset of ovarian activity on the reproductive efficiency of Holstein cows in pastoral conditions. Archivos de Medicina Veterinaria (Chile), 33, 217–226.
2. Clinpro, 2004. Progesterone enzyme immunoassay test kit, No. EH-511, Handbook, (Clinpro International Co. LLC, Union City, CA, USA)
3. Clinpro, 2005. Progesterone enzyme immunoassay test kit, No. EH-511, Handbook (Clinpro International Co. LLC, Union City, CA, USA).
4. Eckersall, P.D. and Harvey, M.J., 1987. The use of bovine plasma progesterone ELISA kits to measure progesterone in equine, ovine and canine plasmas. Veterinary Record, 120(1), 5–8.
5. Edgerton, L.A. and Hafs, H.D., 1973. Serum luteinizing hormone, prolactin, glucocorticoid, and progestin in dairy cows from calving to gestation. Journal of Dairy Science, 56(4), 451–458.