Tolong jelaskan mengenai Catatan dari Ramon I Trencavèl

Fredric L. Cheyette, Ermengard of Narbonne and the World of the Troubadours, Cornell University Press, 2001.

Graham-Leigh, Elaine. The Southern French Nobility and the Albigensian Crusade, The Boydell Press, 2005. .

Kristen di Perang Salib Kedua