Historia Brittonum
The pedigree of king Aella of Deira given in "Historia Brittonum" includes the name "Sguerthing" as great-grandfather of the king, and this has been interpreted as a reference to the Swerting of "Beowulf". The name does not appear in other versions of the royal pedigree and may represent an attempt by the author of "Historia Brittonum" to interpose this heroic character into the royal pedigree.