1. Armitage, P., Berry, G., 1994. Statistical Methods in Medical Research, 3rd Edition. Blackwell Scientific Publications, Oxford.
2. A review of embryonic mortality in cattle;Ayalon;J. Reprod. Fert.,1978
3. Båge, R., 1998. Progesterone levels and oestrus expression in dairy heifers at the time of field insemination. In: Proceedings of the 2nd Conference of the European Society for Domestic Animal Reproduction held in conjunction with the 2nd Central European Conference on Animal Reproduction, Abstracts 18–19, Keszthely, Hungary, 26–28 November 1998.
4. Suprabasal progesterone levels in repeat-breeder heifers during the pro- and oestrus-period;Båge;Theriogenology,1997
5. Progesterone in bovine milk fat;Caudle;Theriogenology,1980