1. Afzal, M., M. Anwar, and M. A. Mirza. (2007). Some factors affecting milk yield and lactation length in Nili Ravi buffaloes. Pakistan Vet. J., 27: 113-117.
2. Bajwa, I. R., M. S Khan, M. A. Khan, and K. Z. Gondal. (2004). Environmental factors affecting milk yield and lactation length in Sahiwal cattle. Pakistan Vet. J. 24: 23-27.
3. Bezdicek, J., Z. Lakoma, and F. Louda. (2008). Comparison between breeding values for milk production and reproduction of bulls of Holstein-Friesian breed in artificial insemination and bulls in natural service. Archiva Zootechnica. 11: 29-34.
4. Chaudhry, M. A. (1992). Factors affecting the lactation length and milk yield in Nili-Ravi buffaloes. Asian Austr. J. Anim. Sci., 5:375-382.
5. Cunningham, E.P. and O. Syrstad. (1987). Crossbreeding Bosindicus and Bostaurus for milk production in the tropics. FAO. Animal Production and Health. Paper No. 68, 90 pp.