APA (7 वां संस्करण) प्रशस्ति पत्र

Wolff, R. P. (1981). About philosophy: About philosophy (2nd ed.). Prentice-Hall.

शिकागो शैली (17वां संस्करण) प्रशस्ति पत्र

Wolff, Robert Paul. About Philosophy: About Philosophy. 2nd ed. Englewood Cliffs, NJ: Prentice-Hall, 1981.

एमएलए (9वां संस्करण) प्रशस्ति पत्र

Wolff, Robert Paul. About Philosophy: About Philosophy. 2nd ed. Prentice-Hall, 1981.