Annales regni Francorum
He is mentioned in the Royal Frankish Annals ("Annales regni Francorum") in entries regarding 818–821. His titles were "Duke of the Guduscani" (a Croatian tribe from Lika and northern Dalmatia) in 818; "Duke of Dalmatia" in 819; "Duke of Dalmatia and Liburnia" in 821. Historiography treats him as a ruler of "Dalmatian Croatia".