Several primary sources exist for Hereward's life. Their accuracy is difficult to judge. They are the version of the "Anglo-Saxon Chronicle" written at Peterborough Abbey (the "E manuscript" or Peterborough Chronicle), the "Domesday Book" (DB), the "Liber Eliensis" (Book of Ely) and, much the most detailed, the "Gesta Herewardi" ("Gesta").