The Alberti Milioli Notarii Regini Liber de Temporibus names "comitissam Ildegarda" as wife of "comes Atto", recording that she built "monasterium de Brixill", and her death "III Id Jan" and burial "in arce Canusina". 1
Marriage Information:
Ildegarde married Cte Adalberto Atto DI REGGIO, son of Sigifredo DI CANOSSA. (Adalberto Atto DI REGGIO was born in Canossa, Italy, died on 13 Feb after 975 and was buried in Church of St Appollonius near Canossa.)
Sources
1 Foundation for Medieval Genealogy, Medlands, Adalberto Atto.