The next book in Mushroom Model Publication [MMP] Samolot po Polsku series is 08. Bartel BM-4.
This is partial text from the full article (usually with photos) at https://aeroscale.net/news/new-book-bartel-bm-4
This is partial text from the full article (usually with photos) at https://aeroscale.net/news/new-book-bartel-bm-4