He was a liturgical reformer, closely tied to the court of Charlemagne. His sacramentary is the only surviving exact copy, made around 812, of the Sacramentarium Hadrianum, sent out by Pope Hadrian I to Charlemagne. 
- Hildoardus, Hildoward, Hildeguard.
- Celia Martin Chazelle, The Crucified God in the Carolingian Era: Theology and Art of Christ's Passion (2001), p. 79.
- Yitzhak Hen, Culture and Religion in Merovingian Gaul, A.D. 481-751 (1995), note p. 58.
- John Michael Wallace-Hadrill, The Frankish Church (1983), p. 212.
- "Archived copy". Archived from the original on 2014-03-18. Retrieved 2008-02-14.CS1 maint: archived copy as title (link)