Columbia subject headings:
Harvard subject headings:
Northmen--Communication.
Scandinavia--History--To 1397.
Scandinavia--Social life and customs.
Scandinavians--Communication.
Trade routes--Baltic Sea.
Vikings--Communication.
Princeton subject headings:
Northmen--Communication.
Scandinavia--History--To 1397.
Scandinavia--Social life and customs.
Scandinavians--Communication.
Trade routes--Baltic Sea.
Vikings--Communication.