R. F. · Robert F. · Robert F. Barkowski
| title | ISBN-13 (ISBN-10) | year of publication |
|---|---|---|
| Crotone 982 | 978-83-11-13732-5 (83-11-13732-3) | 2015 |
| Polabie 983 | 978-83-11-13913-8 (83-11-13913-X) | 2015 |
| Slowianie Polabscy Dzieje zaglady | 978-83-11-13741-7 (83-11-13741-2) | 2015 |