Niewidzialna forteca
| Series | Thorgal |
| Number | Vol. 19 |
| Publisher | Egmont Poland |
| Date | 1995 |
| Type | Comic Book, Trade Paperback |
| Language | Polish |
| Artist | Grzegorz Rosiński |
| Cover Artist | Grzegorz Rosiński |
| Translator | Wojciech Birek |
| Writer | Jean Van Hamme |
| Original Publisher | Le Lombard |
| Printed By | Proost Industries |
| Genre | Fantasy |
| Published in | Poland |
| Pages | 48 |
| ISBN | 83-7123-181-4 |
| Characters | Thorgal Aegirsson, Aaricia, Jolan |
| Notes | Ⓒ G. Rosiński-J. Van Hamme Editions du Lombard, Bruxelles 1993 Ⓒ for the Polish edition by Egmont Polska 1995 Original title: La Forteresse invisible |
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