1. Farooq M, Mian MA, Durrani FR, Syed M: Prevalent diseases and mortality in egg type layers under subtropical environment.Livest Res Rural Dev 2002. Available at: ., [http://www.lrrd.org/lrrd14/4/faro144.htm]
2. Sorensen P: Selection, Environment of Layer, and Response on Nesting Behavious. In Proceedings of the 19th World Poultry Congress, Volume 2. Amsterdam, the Netherlands: World’s Poultry Science Association, Netherlands Branch; 1992:409–412.
3. North MO: Breeder Management. Commercial Chicken Production Manual. The Avi. Publishing Company. Inc, Westport, Connecticut; 1984:240-243. 298-321
4. Farooq M, Mian MA, Faisal S, Durrani FR, Arshad M, Khursid A: Status of broiler breeders stocks in Abbotabad and Mansehra. Sarhad J Agr. 2001, 17 (4): 489-495.
5. Food and Agriculture Organization of the United Nations (FAO): Egg Production. Ch. 1. In Egg Marketing: A Guide for the Production and Sale of Eggs, Food and Agriculture Organization Agricultural Services Bulletin No. 150, 2003. Rome: FAO. Available at: . Accessed on February 26, 2014., [http://www.fao.org/docrep/005/y4628e/y4628e03.htm]