Maiorka, Alex, et al. “Broiler Breeder Age and Dietary Energy Level on Performance and Pancreas Lipase and Trypsin Activities of 7-Days Old Chicks”. International Journal of Poultry Science, vol. 3, no. 3, Feb. 2004, pp. 234–237, https://doi.org/10.3923/ijps.2004.234.237.