J. F. Paulino, J. C. Afonso, J. L. Mantovano, C. A. Vianna, e J. W. S. D. Cunha, “Recovery of Tungsten from Wolframite from the mine of Igarapé Manteiga (Rondonia – Brazil) via acidic leaching”, ien prog rep, nº 1, p. 92, jul. 2015.