Dunbar, C. O. (1960). Historical geology. John Wiley r Sons.
Lua i Stíl Chicago (17ú heag.)Dunbar, Carl O. Historical Geology. John Wiley r Sons, 1960.
Lua MLA (8ú heag.)Dunbar, Carl O. Historical Geology. John Wiley r Sons, 1960.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.