Kusnadi, E., and F. Rahim. “Effect of Floor Density and Feeding System on The Weights of Bursa of Fabricius and Spleen As Well As the Plasma Triiodothyronine Level of Bayang Duck”. Pakistan Journal of Nutrition, vol. 8, no. 11, Oct. 2009, pp. 1743–1746, https://doi.org/10.3923/pjn.2009.1743.1746.