APA (7th ed.) Citation

Callahan, D., & Engelhardt, H. T. (1981). The roots of ethics: Science, religion, and values. Plenum.

Chicago Style (17th ed.) Citation

Callahan, Daniel, and H. Tristram Engelhardt. The Roots of Ethics: Science, Religion, and Values. New York [etc.]: Plenum, 1981.

MLA (9th ed.) Citation

Callahan, Daniel, and H. Tristram Engelhardt. The Roots of Ethics: Science, Religion, and Values. Plenum, 1981.