Gómez-Pinilla, I., Larrea, M.T. and Valle, F.J. 1998. Problematic of the Imini pyrolusites in the production of ferromanganese for metallurgical applications. Revista de Metalurgia. 34, Extra (May 1998), 390–394. DOI:https://doi.org/10.3989/revmetalm.1998.v34.iExtra.778.