(1987). Earth science. Silver Burdett.
Lua i Stíl Chicago (17ú heag.)Earth Science. Morristown, N.J: Silver Burdett, 1987.
Lua MLA (9ú heag.)Earth Science. Silver Burdett, 1987.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.