- Commoner, Barry. The Closing Circle. New York: Bantam Books, 1971, p. 29.
- Donaldson, George E., and Donaldson, Louise E. “Outdoor Education, A Definition.” Journal of the American Association for Health, Physical Education and Recreation (May-June 1958): 17 ff.
- Edwards, Yorke. The Land Speaks: Organizing and Running on an Interpretive System, The National and Provincial Parks Association of Canada. Golden, B.C.: Golden Star Publishing, 1979.
- Muir, John. Cited in Gentle Wilderness. San Francisco: Sierra Club, 1964, intro.
- Tilden, Freeman. Interpreting Our Heritage. Chapel Hill: The University of North Carolina Press, 1957, 1967.
- Zuckerman, Marvin. “The Search For High Sensation.” Psychology Today 11 (Feb. 1978): 38–40.
The Journal of Environmental Education
Volume 14, 1982 - Issue 1