Ma, Junran, Zhao Hechun, and Wang He. “Research on Optimal Environmental Tax, Sub-Optimal Selection and Influencing Factors in China”. International Journal for Innovation Education and Research 7, no. 3 (March 1, 2019): 13–18. Accessed May 19, 2024. https://scholarsjournal.net/index.php/ijier/article/view/1221.