When a sick queen died, a horrible witch strove to become the heir of the throne. The king chose her as his wife, not knowing that she was a witch. But she deceived him completely and transformed the king’s seven sons into swans. The king’s daughter then married and saved her brothers from the nasty queen’s spell by making magic shirts for them which turned them back into princes. This book started in the Russian language for children, and you may find it at the library in the fairy tale section.