«Billung dynasty | German history». Encyclopedia Britannica(engelsk). Besøkt 24. april 2021. «Billung dynasty, the primary ruling dynasty in Saxony in the 10th and 11th centuries. It was founded by Hermann Billung, who in 936 received from the German king (and future emperor) Otto I a march, or border territory, on the lower Elbe River to be held against the pagan Slavic Wends. (---) Herman’s son, Bernhard I (d. 1101), developed his father’s ducal status and title in Saxony and thereafter passed it to his descendants, who continued the struggle against the Slavs. | (---) Bernard I obtained guarantees of the special privileges and customs of the Saxons from the emperor Henry II; Bernard II (d. 1059) obtained similar guarantees from the emperor Conrad II. Both Bernard II and his son Ordulf (d. 1072) had to defend their territories against the encroachments of Adalbert, archbishop of Bremen.»
