Yulyanti, Sylvia, and Rudolf Lumbantobing. “The Moderating Effect of Selling Prices and Buying Prices on the Effect of Copper Hedging on the Profitability of the Copper Division of PT. TMS”. Enrichment : Journal of Management 13, no. 2 (June 5, 2023): 731-742. Accessed April 23, 2026. https://enrichment.iocspublisher.org/index.php/enrichment/article/view/1327.