APA (7th ed.) Citation

Barrett, W. (1964). What is existentialism? Grove Press.

Chicago Style (17th ed.) Citation

Barrett, William. What Is Existentialism? New York: Grove Press, 1964.

MLA (9th ed.) Citation

Barrett, William. What Is Existentialism? Grove Press, 1964.

Warning: These citations may not always be 100% accurate.