Further reading:

Robert Riddick Smith, “Hon. Robert Riddick Prentis,”  The Virginia Law Register, Vol. 10, No. 12 (April 1905), 1111-1114.

Armistead M. Dobie, “Judicial Review of Administrative Action in Virginia,” Virginia Law Review, Vol. 8, No. 8 (June 1922), 557-588.  Analysis of judicial review of decisions of the State Corporation Commission, established in 1903 to oversee the railroad, telegraph, and telephone industries in Virginia. Prentis was chair of the commission from 1907-1916.

Research collections:

University of Virginia (Albert and Shirley Small Special Collections Library)
Charlottesville, Va.
Webb-Prentis Family Papers, 1770-1908.  Collection includes a Letterbook of Robert Riddick Prentis, 1916; finding aid available.