Complete Peerage, Location: Mid-Continent Library, Independence @ Earl of Sussex, The Complete Peerage vol.XIIp1,p.515.
The cited information was published by St. Catherine Press, 29 Great Queen St, Kingsway, W.C., 1959 (Ref: Earl of Sussex, The Complete Peerage vol.XIIp1,p.515.) The author/originator was G.E. Cockayne.