References
- Hungerford , Harold R. and Knapp , Clifford E. 1969 . “Conservation Education: Problems and Strategies.” . The Science Teacher , 36 May : 29
- Hungerford , Harold R. and Litherland , Ralph A. Teacher's Guide to Modules I, II, III, IV and V of the Autonomous Learner Design for Environmental Education By the editors, Science Education, Southern Illinois University, Carbondale, Illinois and Special Services Division, Carbondale Elementary Schools, Carbondale, Illinois, 1973: IM–I, 1
- Breer , Paul E. and Locke , Edwin A. 1965 . Task Experience as a Source of Attitudes , 9 – 10 . Homewood : The Dorsey Press .
- Bisaga , Henry R. 1975 . “Middle School Students' Value Clarification in Environmental Education as a Function of Autonomous Research.” , 115 – 116 . Department of Elementary Education, Southern Illinois University . Unpublished Master's Thesis
- Harmin , Merrill , Kirschenbaum , Howard and Simon , Sidney B. 1973 . Clarifying Values Through Subject Matter , 8 – 38 . Minneapolis, Minnesota : Winston Press .
- Tomera , Audrey N. 1972 . Ecology: A Work Text , 58 – 60 . Portland, Maine : J. Weston Walch, Publisher .