Abdullah, H., N. A. Bakar, M. R. M. Jali, and F. W. Ibrahim. “The Current State of Malaysia’s Journey towards a Green Economy: The Perceptions of The Companies on Environmental Efficiency and Sustainability”. International Journal of Energy Economics and Policy, vol. 7, no. 1, Jan. 2017, pp. 253-8, https://econjournals.com/index.php/ijeep/article/view/3707.