S. Sudrajat, Y. Sukmawan, and S. Sugiyanta, “Influence of Manure, Nitrogen, Phosphorus and Potassium Fertilizer Application on Growth of One-year-old Oil Palms on Marginal Soil in Jonggol, Bogor, Indonesia”, JTCS, vol. 1, no. 2, pp. 18–24, Dec. 2014.