| year of publication | ISBN | author(s) | title |
|---|---|---|---|
| 1998 | 978-0-9585167-0-9 | Rudolf · Powys, Anne Schulz | Pinguone, Kenya: Succulents and Their Environment |
| 2000 | 978-0-9585167-1-6 | Rudolf Schulz and Marlon Machado | Uebelmannia and Their Environment |
| '' | 978-0-9585167-2-3 | Attila · Schulz, Rudolf Kapitany | Succulents for the Garden |