Chalil, Diana, and Riantri Barus. “Analysis of Smallholders’ Progress in Implementing Sustainable Management in North Sumatra, Indonesia”. Indonesian Journal of Agricultural Research 1, no. 3 (February 19, 2019): 246 - 259. Accessed May 2, 2024. https://talenta.usu.ac.id/InJAR/article/view/677.