Adriani S.A. Siahaan, Erwin M. Harahap, Chairani Hanum, Abubakar Karim, Halus Satriawan, and Ernawita. “The Correlation of Elevation, Soil Chemical Properties and Yield of Coffea Arabica L. in Shaded Conditions: Yield of Coffea Arabica L. In Shaded Conditions”. Biological Sciences - PJSIR 65, no. 3 (October 20, 2022): 282–291. Accessed May 17, 2024. http://www.v2.pjsir.org/index.php/biological-sciences/article/view/2987.