Mahzun, R., T. Thamrin, B. Bahruddin, and N. Nofrizal. “Effect of Ecological, Economic and Social Factors on the Implementation of ISO 14001 Environmental Management System in Heavy Industries in Indonesia”. International Journal of Energy Economics and Policy, vol. 10, no. 6, Oct. 2020, pp. 469-75, https://econjournals.com/index.php/ijeep/article/view/8984.