APA (7th ed.) Citation

Gregory, O. (1822). Letters to a friend on the evidences, doctrines and duties of the Christian religion. American Tract Society.

Chicago Style (17th ed.) Citation

Gregory, Olinthus. Letters to a Friend on the Evidences, Doctrines and Duties of the Christian Religion. New York: American Tract Society, 1822.

MLA (8th ed.) Citation

Gregory, Olinthus. Letters to a Friend on the Evidences, Doctrines and Duties of the Christian Religion. American Tract Society, 1822.