Ingeborg of Denmark, queen of France. [Letter to Celestine III, pope, 1195] in Recueil des historiens des Gaules et de la France 19: 314

[Letter from Ingeborg of Denmark, queen of France, to Pope Celestine III]
Philip, who had himself divorced from Ingeborg on the grounds of consanguinity three months after the wedding, has had the queen confined in the abbey of Cisoing, in the diocese of Tournai, from which she laments to the pope.
Online at Epistolae (See also Bibliographia record).