Gordo, E., García-Carcedo, F., & Torralba, J. M. (1998). Tantalum and niobium carbides obtention by carbothermic reduction of columbotantalite ores. Revista De Metalurgia, 34(Extra), 395–399. https://doi.org/10.3989/revmetalm.1998.v34.iExtra.779