Landy , N., and M. Toghyani. “Evaluation the Effects of Dietary Cholecalciferol Substitution With 1alpha-Hydroxycholecalciferol on Performance and Tibia Parameters in Broiler Chickens”. International Journal of Poultry Science, vol. 13, no. 9, Aug. 2014, pp. 515–517, https://doi.org/10.3923/ijps.2014.515.517.