References for John I. 1st Duke, Earl Holland * of Exeter * of Huntingdon
J. Dupont, J. Saillot: Cahiers de Saint-Louis. Nantes, Angers, 1976 etc.
A. Freer: The Descendants of William the Conqueror. http://freepages.genealogy.rootsweb.com/~conqueror/genealogy_html