Werner, A. B. T., Sinclair, W. D., & Amey, E. B. (1998). International strategic mineral issues summary report--tungsten. U.S. G.P.O. U.S. Dept. of the Interior, U.S. Geological Survey.
Cita Chicago (17th ed.)Werner, Antony B. T., W. D. Sinclair, i Earle B. Amey. International Strategic Mineral Issues Summary Report--tungsten. Washington: U.S. G.P.O. U.S. Dept. of the Interior, U.S. Geological Survey, 1998.
Cita MLA (9th ed.)Werner, Antony B. T., et al. International Strategic Mineral Issues Summary Report--tungsten. U.S. G.P.O. U.S. Dept. of the Interior, U.S. Geological Survey, 1998.
Atenció: Aquestes cites poden no estar 100% correctes.