Trziszka, T., Saleh, Y., Kopeae, W., Siewinski, M., & Wesierska, E. (2004). Effect of Hen`s Age on the Level of Cystatin in the Chicken Egg White. International Journal of Poultry Science, 3(7), 471–477. https://doi.org/10.3923/ijps.2004.471.477