Van Thinh, N., Cao Khai , N., Van Quang , N., Cao Khai , N. i Xuan Ha , T. (2022) „Determination of methane content at Maokhe coal mine from curent mining to -450 level in Vietnam”, Inżynieria Mineralna, 2(2). doi: 10.29227/IM-2019-02-51.