Ali, M.N. et al. 2007. Effect of Strain, Type of Natural Antioxidant and Sulphate Ion on Productive, Physiological and Hatching Performance of Native Laying Hens. International Journal of Poultry Science. 6, 8 (Jul. 2007), 539–554. DOI:https://doi.org/10.3923/ijps.2007.539.554.