Barber, Malcolm (NHC Fellow, 1998–99). The Cathars: Dualist Heretics in Languedoc in the High Middle Ages. The Medieval World. London: Longman, 2000. ISBN 9780582256620.
Barber, Malcolm (NHC Fellow, 1998–99). The Cathars: Dualist Heretics in Languedoc in the High Middle Ages. The Medieval World. London: Longman, 2000. ISBN 9780582256620.