Perkasa, A. Y., Utomo, U. and Widiatmoko, T. (2016) “Effect of Various Levels of NPK Fertilizer on the Yield Attributes of Soybean (Glycine max L.) Varieties”, Journal of Tropical Crop Science, 3(1), pp. 7–12. doi: 10.29244/jtcs.3.1.7-12.