Widiyanti, Retno. “Effect of Adding Various Qualities of Litter and Urea on the Growth of Earthworms (Pontoscolex Corethrurus) and Soil Microorganism Populations”. Contributions of Central Research Institute for Agriculture 15, no. 3 (July 30, 2021): 62–66. Accessed April 22, 2026. https://ejournal.cria.or.id/index.php/ccria/article/view/44.