 
| Type | Valeur | 
|---|---|
| Titre | Siward and Waltheof, Earls of Northumberland, in Dugdale’s The Baronage of England, pg. 4-6 [See document in the Memories section] | 
| Dugdale’s The Baronage of England, pg. 4-6 | 
| Siward and Waltheof, Earls of Northumberland, in Dugdale’s The Baronage of England, pg. 4-6 [See document in the Memories section] |