Ervise / Helvise NN, comtesse de Tonnerre

Curators Note: According to a number of 19th-century French local histories, sisters Ervise and Azeka were the heiresses of Bar-sur-Seine who married brothers Renaud and Milon de Tonnerre around 1000 CE. These marriages merged the houses of Tonnerre and Bar-sur-Seine.

• Histoire de la ville et de l'ancien comté de Bar-sur-Seine by Lucien Coutant (1854)
• L'Art de Verifier les Dates des Faits Historiques by Francois Clement (Paris, 1818, pp. 288 ff.)
• Manuel d'histoire, de généalogie et de chronologie de tous les états du globe ..., Volume 2 by AMHJ (Anthony Marinus Hendrik Johan) Stokvis (Leiden, 1889, p. 85): a genealogical chart of the counts of Auxerre, Tonnerre, Bar-sur-Seine, and the counts and dukes of Nevers