APA (7th ed.) Citation

Hughes, G. E., & Londey, D. G. (1965). The elements of formal logic. Methuen.

Chicago Style (17th ed.) Citation

Hughes, George E., and David G. Londey. The Elements of Formal Logic. London: Methuen, 1965.

MLA (9th ed.) Citation

Hughes, George E., and David G. Londey. The Elements of Formal Logic. Methuen, 1965.