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MINING MAGAZINE, TABLE B: 1036 MINES ACCOUNTING FOR 90 PERCENT OF ALL OUTPUT OTHER THAN COAL; SOUTH AMERICA: AR-GENTINA, V. 121, NO. 3, 1969, P. 241.MINING MAGAZINE, CENTRAL AND SOUTH AMERICA: ARGENTINA; V.140, NO. 1, 1979, P. 55.MINING MAGAZINE, TABLE B: 1029 MINES ACCOUNTING FOR 90 PERCENT OF ALL OUTPUT OTHER THAN COAL: SOUTH AMERICA;ARGENTINA, V. 125, NO. 3, 1971, P. 257.UNITED NATIONS SURVEY OF WORLD IRON RESOURCES: OCCURRENCEAND APPRAISAL, NEW YORK, UNITED NATIONS, 1970, P. 479.