APA (7th ed.) Citation

Denny, E. H. (1930). Mine safety and accident economy in Colorado metal mines. [publisher not identified].

Chicago Style (17th ed.) Citation

Denny, Edward H. Mine Safety and Accident Economy in Colorado Metal Mines. Washington, D.C.: [publisher not identified], 1930.

MLA (9th ed.) Citation

Denny, Edward H. Mine Safety and Accident Economy in Colorado Metal Mines. [publisher not identified], 1930.