Subardin, Muhammad, Didik Susetyo, Syamsurijal A. Kadir, and Suhel Suhel. 2018. “Economies of Scale and Efficiency of the Pulp Industry in Indonesia: Cobb-Douglas Cost Function Approach”. International Journal of Economics and Financial Issues 8 (4):284-89. https://econjournals.com./index.php/ijefi/article/view/6724.