1. American Association of School Administrators, Conservation Education in American Schools, American Association of School Administrators, Washington, D. C., 1951, p. 62.
2. Association for Supervision and Curriculum Development of the National Education Association, Large Was Our Bounty: Natural Resources and the Schools, National Education Association, Washington, D. C., 1948, p. 7.
3. Dasmann, Raymond F., Environmental Conservation, John Wiley and Sons, Inc., New York, 1964, pp. 2–3.
4. United States Department of the Interior, Quest for Quality, United States Department of the Interior, Washington, D. C., 1965, p. 8.