Cita APA (7a ed.)

Lewis, H. R. (1979). Unsolvable classes of quantificational formulas. Addison-Wesley Pub. Co.

Cita Chicago Style (17a ed.)

Lewis, Harry R. Unsolvable Classes of Quantificational Formulas. Reading, Mass: Addison-Wesley Pub. Co, 1979.

Cita MLA (9a ed.)

Lewis, Harry R. Unsolvable Classes of Quantificational Formulas. Addison-Wesley Pub. Co, 1979.