1. Crystalization patterns of cervial mucus as related to oestrus in beef cattle;Alliston;J. Anim. Sci.,1958
2. Pregnancy diagnosis in cattle;Arora;Punjab Vet.,1969
3. On the usefulness of cervical secretions for pregnancy diagnosis in cattle;Berchtold;Berl. Münch. Tierärztl. Wschr.,1970
4. Application of the vaginal smear to the diagnosis of pregnancy;Bonime;Amer. J. Obstetr. Gynec.,1949
5. Boorsma , P. 1956 Vaginal smear examination in normal and pathological pregnancy Thesis