Hafvilla: "A Note on Norse Navigation", G. J. Marcus, Speculum, Vol. 30, No. 4 (Oct. 1955), pp. 601–605, Published by: Medieval Academy of America, JSTOR2849616Archived 30 January 2020 at the Wayback Machine (accessed 2 November 2011).
Hafvilla: "A Note on Norse Navigation", G. J. Marcus, Speculum, Vol. 30, No. 4 (Oct. 1955), pp. 601–605, Published by: Medieval Academy of America, JSTOR2849616Archived 30 January 2020 at the Wayback Machine (accessed 2 November 2011).