APA (7th ed.) Citation

Gardner, E. D., Johnson, C. H., & Butler, B. S. (1938). Copper mining in North America. United States Government printing off..

Chicago Style (17th ed.) Citation

Gardner, E. D., Charles H. Johnson, and Bert Sylvenus Butler. Copper Mining in North America. Washington: United States Government printing off., 1938.

MLA (8th ed.) Citation

Gardner, E. D., et al. Copper Mining in North America. United States Government printing off., 1938.