| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| Steps to Good Grammar: 169 Lessons, Exercises, and Tests | 978-0-8251-2876-9 (0-8251-2876-5) | 2005 |
| Understanding and Using Good Grammar: Reproducible Lessons, Exercises, and Tests | 978-0-8251-2877-6 (0-8251-2877-3) | 1997 |
G.S. · G. Schäfer · G. W. · W.S. · W Schäfer