William de Ferrers, Earl of Derby - Pedigree | FamilyCentral
 Abt 1162 - 22 Sep 1247
 Abt 1140 - Aft 31 Dec 1189
 Abt 1157 - Aft 5 Feb 1227/28
 Abt 1080 - Aft 1155
 Abt 1088 - Aft 1149