Stokes, W. L. (1960). Essentials of earth history: An introduction to historical geology (4th ed.). Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)Stokes, William Lee. Essentials of Earth History: An Introduction to Historical Geology. 4th ed. India, Englewood Cliffs, N.J: Prentice-Hall, 1960.
Lua MLA (9ú heag.)Stokes, William Lee. Essentials of Earth History: An Introduction to Historical Geology. 4th ed. Prentice-Hall, 1960.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.