Author
Geological Survey (U.S.)
59
United States. Bureau of Mines
57
Geological Survey (U.S.),
4
Albers, John P. 1919-1986,
1
Frezon, Sherwood E. 1921-
1
Hilgeman, Christin
1
McWilliams, Linda Jansen,
1
National Institute for Occupational Safety and Health. Office for Mine Safety and Health Research,
1
Piper, David Z.,
1
U.S. Census Bureau
1
United States. Bureau of the Census
1