"Þáttr Af Ragnars Sonum" [Tale of Ragnar's sons]. Fornaldarsögur Norðurlanda (in Icelandic). March 1998.
snl.no
Lunga, Peter. "Hardeknud – av England og Danmark" [Harthacnut – of England and Denmark]. Store norske leksikon (in Norwegian). Retrieved December 15, 2016.
web.archive.org
Rory McTurk, "Kings and kingship in Viking Northumbria", [1]