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”, Pakistan Journal of Scientific & Industrial Research, vol. 65, no. 3, pp. 282–291, Oct. 2022.