B. Habib, A., Elham M. Yusif, Salim G.Ahmed, and Haytham H.Abdelwahid. “Impact of Phytase Enzyme Usage on Performance and Egg Quality of Laying Hens ”. Global Journal of Animal Scientific Research, Vol. 9, no. 1, Mar. 2021, pp. 19-21, http://www.gjasr.com/index.php/GJASR/article/view/68.