Friedl, A. E. (2001). Teaching science to children: An inquiry approach (5th ed.). McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)Friedl, Alfred E. Teaching Science to Children: An Inquiry Approach. 5th ed. Boston: McGraw-Hill, 2001.
Lua MLA (9ú heag.)Friedl, Alfred E. Teaching Science to Children: An Inquiry Approach. 5th ed. McGraw-Hill, 2001.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.