Palupi, R., L. Abdullah, D.A. Astuti, and Sumiati. 2014. “High Antioxidant Egg Production Through Substitution of Soybean Meal by Indigofera sp., Top Leaf Meal in Laying Hen Diets”. International Journal of Poultry Science 13 (4): 198–203. https://doi.org/10.3923/ijps.2014.198.203.