Fogelin, R. J. (1987). Understanding arguments: An introduction to informal logic (3ª ed.). Harcourt Brace Jovanovich.
Lua i Stíl Chicago (17ú heag.)Fogelin, Robert J. Understanding Arguments: An Introduction to Informal Logic. 3ª ed. Harcourt Brace Jovanovich, 1987.
Lua MLA (9ú heag.)Fogelin, Robert J. Understanding Arguments: An Introduction to Informal Logic. 3ª ed. Harcourt Brace Jovanovich, 1987.
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