Pennsylvania. Geological Survey, 2nd, 1874-1890.
Karl Krenkler
Pennsylvania
Black Heath Coal Company
Charles Kenneth Sullivan
United States. Bituminous Coal Commission.
Alberta. Scientific and Engineering Services and Research Division
United States. Federal Trade Commission
Illinois. Department of Commerce and Community Affairs. Office of Coal Development and Marketing
Ralph Emmet Brewer
James Washington Paul
Alonzo P. Kratz
FMC Corporation
Conference on Price Research. Committee on Prices in the Bituminous Coal Industry
United States. Bureau of Mines
Richard B. Winston