APA (7th ed.) Citation

Paul, J. W. (1927). Timbering along robbing line; factors influencing falls of roof in coal mines. [publisher not identified].

Chicago Style (17th ed.) Citation

Paul, J. W. Timbering Along Robbing Line; Factors Influencing Falls of Roof in Coal Mines. Washington, D.C.: [publisher not identified], 1927.

MLA (9th ed.) Citation

Paul, J. W. Timbering Along Robbing Line; Factors Influencing Falls of Roof in Coal Mines. [publisher not identified], 1927.