References for Margaret de Clifford
Sir B.Burke:
The Dormant and Extinct Peerage.
London, 1866
Sir B.Burke:
Burke's Peerage and Baronetage.
London, 1999
J.W. v.Imhof:
Regum pariumque Magnae Britanniae historia genealogica, tab 137.
Nürnberg, 1690