Malau, Sabam, and Pandianganand Samse. 2018. “Morphological Variation in Arabica Coffee (Coffea Arabica L.) Growing in North Sumatra Indonesia”. Jurnal Agronomi Indonesia (Indonesian Journal of Agronomy) 46 (3), 314-21. https://doi.org/10.24831/jai.v46i3.19342.