P. Dharma Rao
Ernst Klein
International Conference on Bituminous Coal (2nd 1928 Pittsburgh)
Charles Edward Augustine
United States. National Recovery Administration. Research and Planning Division. Bituminous Coal Code Section
United States. National Recovery Administration. Research and Planning Division. Bituminous Coal Section
Pa.) International Conference on Bituminous Coal (3rd 1931 Pittsburgh
Grzegorz J. Nowak
Pa.) International Conference on Bituminous Coal (2nd 1928 Pittsburgh
Henry Beebee Carrington
Viktoras W. Skema
United States. Office of Internal Revenue
S. Parkash
Pennsylvania. Bureau of Topographic and Geologic Survey
Hanʼguk Tongnyŏk Chawŏn Yŏnʼguso
Chamber of Commerce of the United States of America. Natural Resources Production Department
National Coal Association. Bituminous Coal Institute
United States. National Recovery Administration
Leo Holdredge