Author
Nature Conservancy (U.S.)
2
American Chemical Society. Cellulose, Paper, and Textile Division
1
Brandywine Valley Association
1
Brinkley, Douglas
1
Clepper, Henry, 1901-1987
1
Forest History Society
1
Freeman, Orville L.
1
Frome, Michael
1
Hopkins, Alix W.
1
Indian Education Resources Center. Branch of Curriculum
1
Koelsch, William A.
1
Maunder, Elwood R.
1
Mitchell, Lee Clark, 1947-
1
Natural Lands Trust
1
Pennsylvania Audubon Society
1
Pennsylvania Land Trust Association
1
Pennsylvania. Bureau of State Parks
1
Pennsylvania. Department of Conservation and Natural Resources
1
Pennsylvania. Office of State Planning and Development
1
Pennypack Watershed Association
1
Philadelphia Conservationists, Inc
1
Philadelphia Record
1
Rosenkrantz, Barbara Gutmann
1
Ruppert, Estelle
1
Sierra Club
1
Sierra Club Pennsylvania Chapter
1
Sierra Club Southeastern Pennsylvania Chapter
1
Speakman, Joseph M., 1940-
1
Steidle, Edward, 1887-1977
1
Williams, John Covington, 1911-
1