| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| The Natural Superiority of Mules | 978-1-59228-864-9 (1-59228-864-2) | 2006 |
| The Natural Superiority of Mules: A Celebration of One of the Most Intelligent, Sure-Footed, and Misunderstood Animals in the World | 978-1-63450-786-8 (1-63450-786-X) | 2016 |