Stenberger, M., Die Schatzfunde Gotlands der Wikingerzeit, II, Lund, 1947; Hubert, J., Europe of the Invasions, New York, 1969; Arrhenius, B., Merovingian Garnet Jewellery, Stockholm, 1985; Rademacker, F., Frankische Goldscheidenfibeln, Munich, 1940; Laszio, G., The Art of the Migration Period, Miami, 1970; and twenty-five others of similar interest (30)