- Allen C. Guelzo, For the Union of Evangelical Christendom: The Irony of the Reformed Episcopalians (University Park, PA: Pennsylvania State University Press, 1994).
- “Bishop Robert Livingston Rudolph, 1865–1930” in RESume (Fall, 1981), pp. 1ff.
- Raymond A. Acker, A History of the Reformed Episcopal Seminary 1886–1964 (Phila.: Theological Seminary of the Reformed Episcopal Church, 1965).