| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| Step by Step in Esperanto | 978-0-85230-071-8 (0-85230-071-9) | 1979 |
| Step by Step in Esperanto: A Textbook for English-Speaking Students for Class Teaching or Home Study With Graduated Reading Matter Numerous Exercises, and Index | 978-0-939785-01-8 (0-939785-01-3) | 1991 |