Author
Metropolitan Edison Company (Reading, Pa.)
2
Newcomen Society in North America
2
Christesen, Russell J.
1
Keller, Charles., 1868-
1
Lee, William S.
1
Penn Central Light and Power Company
1
Pennsylvania Water & Power Co
1
Philadelphia Electric Company
1
Pinchot, Gifford, 1865-1946
1
Stern & Silverman (Philadelphia)
1
United States. Army. Corps of Engineers
1
Wallace, William, 1926-
1