References
- Hofstad , M. S. 1978 . Diseases of Poultry, , 7th ed. , Ames, Iowa : Iowa State University Press .
- NRC . 1971 . Nutrient Requirements of Poultry, , 6th ed. , Washington, DC : National Academy of Science—National Research Council .
- Price , C. J. and Reed , J. E. 1971 . Poultry Husbandry II , Rome : UN Food and Agriculture Organisation .