APA (7th ed.) Citation

Hughes, G. E., & Cresswell, M. J. (1985). An introduction to modal logic. Methuen.

Chicago Style (17th ed.) Citation

Hughes, George E., and Maxwell J. Cresswell. An Introduction to Modal Logic. London u.a: Methuen, 1985.

MLA (9th ed.) Citation

Hughes, George E., and Maxwell J. Cresswell. An Introduction to Modal Logic. Methuen, 1985.