Book
Die Katharer
Foundational German monograph on the Cathars, published in the Monumenta Germaniae Historica Schriften series.
Where to find it
- Monumenta Germaniae Historica - Schriften der MGH series listing
- Google Books record - Borst, Die Katharer (Hiersemann 1953)
- WorldCat record - Die Katharer (OCLC 180503319)
- Internet Archive scan - Die Katharer (borrow/controlled digital lending)
- Review by Walter Ullmann, Journal of Ecclesiastical History 7.1 (1956), 103-104