J. H. Kurtz, Church History (Volumes 1-3)
“ Of these brotherhoods, during the 12th century, the Waldensians formed the heart and core. Their precursors were the Petrubrusians [Petrobrusians] , the Apostolic Brothers, the Arnoldists, the Humiliati, etc.; their successors and spiritual kinsmen were the heretical Beghards and Lollards, the Spirituals together with Marsilius of Padua and King Louis of Bavaria, the German mystics, the Friends of God and Winkelers, the Dutch Brethren of the Common Life, and, in specially close association with the German Waldensians, the Bohemian and Moravian Brethren ”
