APA (7th ed.) Citation

Posner, R. A. (1990). The problems of jurisprudence. Harvard University Press.

Chicago Style (17th ed.) Citation

Posner, Richard A. The Problems of Jurisprudence. Cambridge, Mass.: Harvard University Press, 1990.

MLA (9th ed.) Citation

Posner, Richard A. The Problems of Jurisprudence. Harvard University Press, 1990.