John Ruhlin · Lioncrest Publishing
| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| Giftology: The Art and Science of Using Gifts to Cut Through the Noise, Increase Referrals, and Strengthen Client Retention | 978-1-7320956-0-1 (1-7320956-0-4) | 2018 |
| Giftology: The Art and Science of Using Gifts to Cut Through the Noise, Increase Referrals, and Strengthen Retention | 978-1-61961-433-8 (1-61961-433-2) | 2016 |