Suriyanti, Suriyanti, et al. “Planning Strategy of Operation Business and Maintenance by Analytical Hierarchy Process and Strength, Weakness, Opportunity, and Threat Integration for Energy Sustainability”. International Journal of Energy Economics and Policy, vol. 10, no. 4, May 2020, pp. 221-8, https://mail.econjournals.com/index.php/ijeep/article/view/9267.