Annales regni Francorum
The story is repeated in an 812 entry of the "Annales Fuldenses". This is not surprising as the entries of the "Annales Fuldenses" from 714 to the 830s were adopting material from earlier sources, including the Royal Frankish Annals. The Gesta Hammaburgensis ecclesiae pontificum by Adam of Bremen mentions "Sigafrid et Anulo, nepotes Godafridi", which would make both Anulo and Sigifrid "nepotes" (plural of nepos) of Gudfred. The "Royal Frankish Annals" then note "Heriold and Reginfrid, kings of the Danes, send an embassy to the emperor [Charlemagne], asking for peace and requesting that their brother Hemming be released." The text makes clear that Hemming was held prisoner by Charlemagne but leaves unclear when Hemming was captured and under what circumstances.