References for Roger 4th Earl, Earl Mortimer * of March * of Ulster
H. Grote: Stammtafeln. Leipzig, 1877
M.A.H., Marquis de Ruvigny: The Plantagenet roll of the blood royal, Essex Volume. London, Edinburgh, 1908
F.M.Powicke, E.B.Fryde: Handbook of British Chronology. London, 1961
A.M.Stokvis: Manuel d'histoire. Amsterdam, 1966