Analysis of information sources in references of the Wikipedia article "Ljudevit (Lower Pannonia)" in English language version.
... in the unsuccessful rebellion of Ljudevit of Posavia (Ljudevit Posavski), leader of the Pannonic Slavs, against the Franks, the semi-independence of the land was definitely at an end. From 828 onward it was administered by Bavarian counts.
The report refers to the uprising of Liudewitus, dux Pannoniae inferioris (Ljudevit Posavski), which was joined by the inhabitants of Carniola (Annales regni Francorum, ad a. 818 — 823).