Cambridge University Press · Klett
| title | ISBN-13 (ISBN-10) | year of publica- tion | other author(s) | |
|---|---|---|---|---|
| Objective Proficiency Workbook with answers | 978-0-521-00033-8 (0-521-00033-5) | 2002 | ||
| Objective Proficiency: Workbook with answers with Audio CD | 978-3-12-540146-4 (3-12-540146-1) | 2013 | Peter Sunderland | |
| Objective Proficiency Workbook without answers | 978-0-521-00032-1 (0-521-00032-7) | 2002 | ||