| year of publication | ISBN | author(s) | title |
|---|---|---|---|
| 1988 | 978-0-9620685-0-8 | Robert Folzenlogen | A Birder's Guide to the Cincinnati Tristate |
| 1993 | 978-0-9620685-4-6 | Darcy Folzenlogen ยท Robert Folzenlogen | Guide to American Zoos and Aquariums |
| 1996 | 978-0-9620685-9-1 | Robert Folzenlogen | Colorado's Year, a Guide to Nature's Highlights |