Tulin, E. E. (1983) “EFFECT OF FERTILIZER APPLICATION ON THE YIELD AND PROTEIN CONTENT OF SOYBEAN HARVESTED AT VARIOUS STAGES OF MATURITY”, Annals of Tropical Research, 5(3&4), pp. 117–125. Available at: https://atr.vsu.edu.ph/article/view/726 (Accessed: 5 December 2025).