Educational Facilities Laboratories, National Education Association of the United States, United States. National Park Service, & Ezersky, E. (1972). Environmental education. S.n.
Citazione stile Chigago Style (17a edizione)Educational Facilities Laboratories, National Education Association of the United States, United States. National Park Service, e Eugene Ezersky. Environmental Education. New York: S.n, 1972.
Citatione MLA (9a ed.)Educational Facilities Laboratories, et al. Environmental Education. S.n, 1972.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.