Principles of mining; valuation, organization and administration; copper, gold, lead, silver, tin and zinc, Herbert C. Hoover ... Hoover, Herbert, 1874-1964. Mines and mineral resources. Mining engineering. Mineral industries Finance. TN145 .H7 549.12 HOP New York : Hill Publishing Company, 1909. 1909. 1909 Text iii-vii, 199 p. : eng