APA (7th ed.) Citation

Clarke, J., & Lindsey, T. An answer to the question, Why are you a Christian? (The sixth edition.).

Chicago Style (17th ed.) Citation

Clarke, John, and Theophilus Lindsey. An Answer to the Question, Why Are You a Christian? The sixth edition.

MLA (9th ed.) Citation

Clarke, John, and Theophilus Lindsey. An Answer to the Question, Why Are You a Christian? The sixth edition.

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