Purwanto, Iir, et al. “Growth of Pepper Plant (Piper Nigrum Linn.) After Application of Organic Fertilizer Leaves of Gamal (Gliricidia Sepium (Jacq) Kunth.)”. Jurnal Biologi Tropis, vol. 21, no. 3, Sept. 2021, pp. 854-62, doi:10.29303/jbt.v21i3.2838.