Umar, S. ., & Kadeko, I. . (2015). Model of Tree Shade Value by Contingent Valuation Technique on the Cocoa Agroforestry of Central Sulawesi Province. Journal of Asian Scientific Research, 5(9), 439–451. https://doi.org/10.18488/journal.2/2015.5.9/2.9.439.451