Cita APA (7a ed.)

Hughes, G. E., & Cresswell, M. (1996). An introduction to modal logic. Routledge.

Cita Chicago Style (17a ed.)

Hughes, G. E., y M.J Cresswell. An Introduction to Modal Logic. London [etc.]: Routledge, 1996.

Cita MLA (9a ed.)

Hughes, G. E., y M.J Cresswell. An Introduction to Modal Logic. Routledge, 1996.