National Environmental Education Development. National Park Foundation. (1971). Adventure in environment: Teacher's guide. Silver Burdett.
Lua i Stíl Chicago (17ú heag.)National Environmental Education Development. National Park Foundation. Adventure in Environment: Teacher's Guide. Morristown, NJ: Silver Burdett, 1971.
Lua MLA (9ú heag.)National Environmental Education Development. National Park Foundation. Adventure in Environment: Teacher's Guide. Silver Burdett, 1971.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.