Fogelin, R. J. (1987). Understanding arguments: An introduction to informal logic (3ª ed.). Harcourt Brace Jovanovich.
Dyfyniad Arddull ChicagoFogelin, Robert J. Understanding Arguments: An Introduction to Informal Logic. 3ª ed. Harcourt Brace Jovanovich, 1987.
Dyfyniad MLAFogelin, Robert J. Understanding Arguments: An Introduction to Informal Logic. 3ª ed. Harcourt Brace Jovanovich, 1987.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.