"Agatha Kaptein"(Dutch). Alle Begijnen van Amsterdam. genealogieonline. Retrieved 2009-01-21.
newadvent.org
See for instance, Algemene Winkler Prins (1956) (in Dutch) which remarks that no link has been found between Beguines and the Albigensian heresy. An example of an encyclopedia that does not refer at all to a possible link with the Cathars is the "Catholic Encyclopedia: Beguines, Beghards". New Advent.