Penguin · Yale University Press
| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| The Hidden Tradition in Europe: The Secret History of Medieval Christian Heresy | 978-0-14-019319-0 (0-14-019319-7) | 1994 |
| The Other God: Dualist Religions from Antiquity to the Cathar Heresy | 978-0-300-08253-1 (0-300-08253-3) | 2000 |