APA (7th ed.) Citation

Tillich, P. (1969). What is religion? Harper & Row Publishers.

Chicago Style (17th ed.) Citation

Tillich, Paul. What Is Religion? Harper & Row Publishers, 1969.

MLA (8th ed.) Citation

Tillich, Paul. What Is Religion? Harper & Row Publishers, 1969.

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