| Managing to keep the customer | | Tiada | 1988 | 1555420273 |
| Can you keep a secret? | Transworld Publishers | Tiada | 2003 | 978-0-552-15082-8 |
| The right way to keep pet fish | | Tiada | 1975 | |
| Write tight : how to keep your prose sharp, and concise | Writer's Digest Books | Tiada | 1993 | 0-89879-548-6 |
| How to win customers and keep them for life | | Tiada | 1990 | 0-86188-970-3 |