G. Akpa, J. Kaye, I. Adeyinka, and M. Kabir, “The Relationships Between Laying Age and Repeatability of Egg Quality Traits in Japanese Quails (Coturnix coturnix japonica()”, Int. J. Poult. Sci., vol. 7, no. 6, pp. 555–559, May 2008, doi: 10.3923/ijps.2008.555.559.