References
- N.Z. Dairy Board . 1948 . N.Z. Dairy Board 24th Annual Report 48 – 48 .
- N.Z. Dairy Board . 1961 . N.Z. Dairy Board 37th Annual Report 81 – 81 .
- N.Z. Dairy Board . 1972 . N.Z. Dairy Board 48th Farm Production Report 30 – 30 .
- Roberts , S. J. 1971 . Veterinary Obstetrics and Genital Diseases (Theriogenology) , 2nd Edition , Ithaca : S. J. Roberts . 90 pp
- Salisbury , G. W. and VanDemark , N. L. 1961 . Physiology of Reproduction and Artificial Insemination of Cattle , San Francisco : W. H. Freeman and Company . 94 pp