| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| Christian and Islamic Spirituality: Sharing a Journey | 978-0-8091-3426-7 (0-8091-3426-8) | 1993 |
| Christian Mysticism East and West: What the Masters Teach Us | 978-0-8091-3823-4 (0-8091-3823-9) | 1998 |
| Medieval and Renaissance Spirituality: Discovering the Treasures of the Great Masters | 978-0-8091-4659-8 (0-8091-4659-2) | 2010 |