Cita APA (7a ed.)

U.S.Bureau of Mines. (1991). Mineral Commodity Summaries,1991. U.S.Bureau of Mines.U.S.Geological Survey.

Cita Chicago Style (17a ed.)

U.S.Bureau of Mines. Mineral Commodity Summaries,1991. Washington - EEUU: U.S.Bureau of Mines.U.S.Geological Survey, 1991.

Cita MLA (8a ed.)

U.S.Bureau of Mines. Mineral Commodity Summaries,1991. U.S.Bureau of Mines.U.S.Geological Survey, 1991.