Montgomery, C. W., & Dathe, D. (1994). Earth, then and now (2nd ed.). W. C. Brown.
Lua i Stíl Chicago (17ú heag.)Montgomery, Carla W., agus David Dathe. Earth, Then and Now. 2nd ed. Dubuque, Iowa: W. C. Brown, 1994.
Lua MLA (9ú heag.)Montgomery, Carla W., agus David Dathe. Earth, Then and Now. 2nd ed. W. C. Brown, 1994.
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