Abraham Lincoln the Christian. By William J. Johnson. New York and Cincinnati: The Abingdon Press, 1913.
The Later Life and Religious Sentiments of Abraham Lincoln. By Rev. James A. Reed. Scribner's Monthly, 1873, pp. 333-344.
Lincoln's Religious Belief. By B. F. Irwin. Article in the Illinois State Journal of May 16, 1874. Manuscript copy.
More Testimony. Letter from Hon. William Reid, U. S. Consul at Dundee, Scotland. Article in Portland Oregonian, March 4, 1874. Copied in Illinois State Journal. Manuscript copy.
Abraham Lincoln's Religion. By Madison C. Peters. Boston: Richard G. Badger, The Gorham Press, 1909.
Lincoln and the Church. Article by John G. Nicolay and John Hay in Century, August, 1889.
The Record of a Quaker Conscience. By Cyrus Pringle. New York: Macmillan Company, 1918 (Lincoln and the Quakers).
The Conversion of Lincoln. By Rev. Edward L. Watson, New York, Christian Advocate, November 11, 1909.
The Religious Beliefs of Abraham Lincoln. By R. C. Roper. Article in The Open Court.
Lincoln's Religious Faith and Principles. By Thomas D. Logan, D.D. The Interior, February 11, 1909.