Longwell, C. R., Knopf, A., Flint, R. F., Schuchert, C., & Dumbart, C. O. (1939). A textbook of geology (2a. ed.). John Wiley.
Lua i Stíl Chicago (17ú heag.)Longwell, Chester Ray, Adolph Knopf, Richard Foster Flint, Charles Schuchert, agus Carl O. Dumbart. A Textbook of Geology. 2a. ed. Nueva York: John Wiley, 1939.
Lua MLA (9ú heag.)Longwell, Chester Ray, et al. A Textbook of Geology. 2a. ed. John Wiley, 1939.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.