Cooper, J. D. (1986). A Trip Through Time: Principle Of Historical Geology. Merril Publishing Company.
Lua i Stíl Chicago (17ú heag.)Cooper, John D. A Trip Through Time: Principle Of Historical Geology. Merril Publishing Company, 1986.
Lua MLA (8ú heag.)Cooper, John D. A Trip Through Time: Principle Of Historical Geology. Merril Publishing Company, 1986.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.