Mullin, R. P. (2007). The soul of classical American philosophy: The ethical and spiritual insights of William James, Josiah Royce, and Charles Sanders Peirce. State University of New York Press.

Mullin, Richard P. The Soul of Classical American Philosophy: The Ethical and Spiritual Insights of William James, Josiah Royce, and Charles Sanders Peirce. Albany: State University of New York Press, 2007.

Mullin, Richard P. The Soul of Classical American Philosophy: The Ethical and Spiritual Insights of William James, Josiah Royce, and Charles Sanders Peirce. State University of New York Press, 2007.