Graf, J.L., Jr. Rare earth element evidence of origin and depositional environment of late Proterozoic ironstone beds and manganese-oxide deposits, SW Brazil and SE Bolivia - Oxford Pergamon March 1994 - pp. 115-133 ilus. ISSN: 0895-9811 Subjects--Topical Terms: EXPLORACION MINERAMANGANESOOXIDO DE MANGANESOPALEOPROTEROZOICOPROSPECCIÓN GEOQUÍMICAROCAS FERRUGINOSASTIERRAS RARAS Subjects--Geographic Terms: BOLIVIABRASILMATO GROSSOSANTA CRUZ