APA (7th ed.) Citation

Locke, J., & Berkeley, G. (1990). A letter concerning toleration. Great books of the Western world.

Chicago Style (17th ed.) Citation

Locke, John, and George Berkeley. "A Letter Concerning Toleration." Great Books of the Western World 1990.

MLA (9th ed.) Citation

Locke, John, and George Berkeley. "A Letter Concerning Toleration." Great Books of the Western World, 1990.

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