Buanawaty, Puspaning, and Fithra Faisal Hastiadi. “The Impact of Kyoto Protocol on Environment Quality in the Free Trade Era: The Case of G20 Countries”. International Journal of Economics and Financial Issues, vol. 7, no. 3, June 2017, pp. 36-42, https://econjournals.com.tr/index.php/ijefi/article/view/4346.