Woolverton, J. F. (2005). Robert H. Gardiner and the reunification of worldwide Christianity in the Progressive Era. University of Missouri Press.

Woolverton, John Frederick. Robert H. Gardiner and the Reunification of Worldwide Christianity in the Progressive Era. Columbia, Mo.: University of Missouri Press, 2005.

Woolverton, John Frederick. Robert H. Gardiner and the Reunification of Worldwide Christianity in the Progressive Era. University of Missouri Press, 2005.