Gilbert, C. M., & Christensen, M. N. j. a. (1967). Physical geology: Laboratory course (2nd ed.). McGraw-HIll.
Lua i Stíl Chicago (17ú heag.)Gilbert, Charles Mervin, agus Mark N. jt. author Christensen. Physical Geology: Laboratory Course. 2nd ed. New York: McGraw-HIll, 1967.
Lua MLA (9ú heag.)Gilbert, Charles Mervin, agus Mark N. jt. author Christensen. Physical Geology: Laboratory Course. 2nd ed. McGraw-HIll, 1967.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.