van Wyk, G., V. Naidoo, and E. I. Edoun. “Guiding Principles for Establishing Energy Consumption Reduction and Increase Production Performance in Manufacturing”. International Journal of Energy Economics and Policy, vol. 11, no. 1, Dec. 2020, pp. 502-15, https://www.econjournals.com/index.php/ijeep/article/view/8007.