Tolong jelaskan mengenai Rujukan dari Ragnar Lodbrok

Forte, Angelo, Richard Oram, and Frederik Pedersen. Viking Empires. Cambridge University Press, 2005.

Schlauch, Margaret, trans. The Saga of the Volsungs: the Saga of Ragnar Lodbrok together with the Lay of Kraka. New York: American Scandinavian Fndn., 1964.