Thai, Cam Tu, Dinh Phong Nguyen, Phi Hung Tran, Ba Phu Dinh, Thi Tu Anh Tran, Le My Nhan Nguyen, and Thi Le Na Pham. 2021. “Study to Propose an Environmental Key Performance Index for Oil and Gas Companies in Vietnam”. Petrovietnam Journal 4 (April), 47-52. https://doi.org/10.47800/PVJ.2021.04-06.