Innocent III, Pope. [Letter to Ingeborg of Denmark, queen of France, 1205] in Patrologiae cursus completus. Series Latina (Patrologia Latina) 215: 680

[Letter from Pope Innocent III to Ingeborg of Denmark, queen of France]
The pope seems to have been worn down by Philip and offers only spiritual comfort to the queen, though he did not in fact give up her cause.
Online at Epistolae (See also Bibliographia record).