Chamber of Commerce of the United States of America. Natural Resources Department
Viktoras W. Skema
United States. National Bureau of Standards
Reinhardt Thiessen
Walter Henry Voskuil
United States. Congress. House. Committee on Ways and Means
C. M. McCulloch
Black Heath Coal Company.
Unknown Author
United States. Federal Trade Commission.
Thiessen, Reinhardt
United States. National Bituminous Coal Commission
Richard Cowling Taylor
Walton Hale Hamilton
William Blose Reed
Hartmut Dressler
George C Sprunk
S. H. Katz