| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| HARDER AND STRONGER: Best POWERFUL and LASTING ERECTION Solution | 978-1-0709-6061-6 (1-0709-6061-6) | 2019 |
| HARDER AND STRONGER: Best POWERFUL and LASTING ERECTION Solution | 978-1-0709-6063-0 (1-0709-6063-2) | 2019 |