Callmer, J. (1977). Trade beads and bead trade in Scandinavia, ca. 800-1000 A.D. Rudolf Habelt Verlag.
Cita Chicago Style (17a ed.)Callmer, Johan. Trade Beads and Bead Trade in Scandinavia, Ca. 800-1000 A.D. Bonn: Rudolf Habelt Verlag, 1977.
Cita MLA (8a ed.)Callmer, Johan. Trade Beads and Bead Trade in Scandinavia, Ca. 800-1000 A.D. Rudolf Habelt Verlag, 1977.
Precaución: Estas citas no son 100% exactas.