LINDA SIPAYUNG, M. et al. 2021. Coffee Business Development Index Analysis Arabica (Coffea Arabica) in Purba District, Simalungun Regency, North Sumatra Province. Journal of Environmental and Agricultural Studies. 2, 2 (Oct. 2021), 36–49. DOI:https://doi.org/10.32996/jeas.2021.2.2.4.