M W ยท M. Williams
| title | ISBN-13 | year of publication |
|---|---|---|
| Echo 2 CD | 978-0-435-38934-5 | 2005 |
| Echo Express 1 CD | 978-0-435-38908-6 | 2004 |
| Echo Express 2 Cassettes | 978-0-435-38966-6 | 2005 |
| Echo Express 2 CDs | 978-0-435-38962-8 | 2005 |
| Echo Express 2 Teacher's Guide | 978-0-435-38952-9 | 2005 |