APA

Campbell M. H. . B. J. A., . (1929). The coal fields of the united states. Washington: Government Printing Office.

Chicago

Campbell Marius H Bownocker J A, . 1929. The coal fields of the united states. Washington: Government Printing Office.

Harvard

Campbell M. H. . B. J. A., . (1929). The coal fields of the united states. Washington: Government Printing Office.

MLA

Campbell Marius H Bownocker J A, . The coal fields of the united states. Washington: Government Printing Office. 1929.