Petersen, M. S., & Rigby, J. K. (1970). Interpreting earth history, a manual in historical geology. W. C. Brown Co..
Lua i Stíl Chicago (17ú heag.)Petersen, Morris S., agus J. Keith Rigby. Interpreting Earth History, a Manual in Historical Geology. Dubuque, Iowa: W. C. Brown Co., 1970.
Lua MLA (8ú heag.)Petersen, Morris S., agus J. Keith Rigby. Interpreting Earth History, a Manual in Historical Geology. W. C. Brown Co., 1970.
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