Francis، P. R.، و Alla، H. W. (2005). The Effect of Feeding Different Levels of Protein on Egg Production of Medium Hybrid Layers During Cool and Hot Seasons. مجلة دراسات حوض النيل، مج4, ع7 ، 38 - 51. مسترجع من http://search.mandumah.com/Record/608357
Francis، Peter R.، و Husina Waggee Alla. "The Effect of Feeding Different Levels of Protein On Egg Production of Medium Hybrid Layers During Cool and Hot Seasons." مجلة دراسات حوض النيل مج4, ع7 (2005): 38 - 51. مسترجع من http://search.mandumah.com/Record/608357