| title | ISBN-13 (ISBN-10) | year of publica- tion | other author(s) |
|---|---|---|---|
| Purple Goldfish Workbook: 10 Ways to Attract Raving Customers | 978-1-7326652-8-6 (1-7326652-8-1) | 2019 | Evan Carroll |
| Yellow Goldfish: Nine Ways to Increase Happiness in Business to Drive Growth, Productivity, and Prosperity | 978-1-7326652-0-0 (1-7326652-0-6) | 2018 | Rosaria Cirillo Louwman |