Thi, H. D., K. A. Vu Thi, D. L. Phuong, V. P. Thu, and C. H. T. Minh. “Impact of Environmental Tax Collection on CO2 Emission in Vietnam”. International Journal of Energy Economics and Policy, vol. 10, no. 6, Oct. 2020, pp. 299-04, https://www.econjournals.com/index.php/ijeep/article/view/10153.