References
- Mahaffey , Ben D. August 1972 . “A Study of Professional Recommendations for Curricular Guidelines of Environmental Interpreters.” , August , College Station, Texas : Department of Curriculum and Instruction, Texas A&M University . Unpublished Ph.D. Dissertation
- Mullins , Gary W. May 1975 . “A Survey of Resource Materials for Environmental Interpreters.” , May , College Station, Texas : Department of Recreation and Parks, Texas A&M University . Unpublished Masters Thesis