APA (7th ed.) Citation

De Ruggiero, G. (2001). Existentialism or, The philosophy of existence. Living Time.

Chicago Style (17th ed.) Citation

De Ruggiero, Guido. Existentialism or, The Philosophy of Existence. London: Living Time, 2001.

MLA (9th ed.) Citation

De Ruggiero, Guido. Existentialism or, The Philosophy of Existence. Living Time, 2001.

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