Pho, N.V., Xuan, P.T. and Dang, P.T. 2018. Occurrence of supergene nickel ores in the Ha Tri Massive, Hoa An District, Cao Bang Province. Vietnam Journal of Earth Sciences. 40, 2 (May 2018), 153–164. DOI:https://doi.org/10.15625/0866-7187/40/2/11676.