| title | ISBN-13 (ISBN-10) | year of publica- tion | other author(s) |
|---|---|---|---|
| Five Keys to Powerful Business Relationships: How to Become More Productive, Effective and Influential | 978-0-07-178388-0 (0-07-178388-1) | 2013 | Joseph Sperry · Steve Vucelich |
| The Seven Keys to Managing Strategic Accounts | 978-0-07-141752-5 (0-07-141752-4) | 2003 | Joseph Sperry · Samuel Reese |