 
| Type | Valeur | 
|---|---|
| Titre | Robert de Ferrers, Earl of Derby, in Cokayne's Complete Peerage, Vol. 3, pg. 67 [See document in the Memories section] | 
| Personnes | 
|---|
|  BERTHA (DE FLECHIN) | 
| Cokayne's Complete Peerage, Vol. 3, pg. 67 | 
| Robert de Ferrers, Earl of Derby, in Cokayne's Complete Peerage, Vol. 3, pg. 67 [See document in the Memories section] |