Ernita, Y., R. A. H. Guna, S. Santosa, and N. Nofialdi. “Analysis of Cocoa Industry Development Factor With System Approach in West Sumatera, Indonesia”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 36, no. 3, Oct. 2017, pp. 122-33, https://gssrr.org/index.php/JournalOfBasicAndApplied/article/view/8192.