Syah S, Anggeraini F, Tamba DP. The Influence of Employee Productivity and Operational Costs on Increasing Revenue PT. Diamond National Iron Industry Medan. IJEC [Internet]. 2024 Aug. 15 [cited 2024 Sep. 1];3(2):883-97. Available from: https://ejournal.ipinternasional.com/index.php/ijec/article/view/1040