NGUYEN, L. H. S.; HOANG, A. Q. Literature review method of mining underground coal gasification. Journal of Technical Education Science, [S. l.], v. 9, n. 1, p. 84–87, 2014. Disponível em: https://www.jte.edu.vn/index.php/jte/article/view/684. Acesso em: 7 apr. 2026.