Balkan, M., R. Karakas, and M. Biricik. “Changes in Eggshell Thickness, Shell Conductance and Pore Density During Incubation in the Peking Duck (Anas Platyrhynchos F. Dom)”. Ornis Fennica, vol. 83, no. 3, Sept. 2006, pp. 117–123, https://ornisfennica.journal.fi/article/view/133662.