Copi, I. M., & Cohen, C. (1994). Introduction to logic. [s.n.].
Cita Chicago (17th ed.)Copi, Irving M., i Carl Cohen. Introduction to Logic. Singapore: [s.n.], 1994.
Cita MLA (9th ed.)Copi, Irving M., i Carl Cohen. Introduction to Logic. [s.n.], 1994.
Atenció: Aquestes cites poden no estar 100% correctes.