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Books about Piwnik:
PIWNIK Marie-Hélène O anonimo Journal portugais du XVIIIème siècle (1752-1754) EDITION ORIGINALE ENVOI AUTOGRAPHE... by PIWNIK Marie-Hélène (1979)
Ponury Major Jan Piwnik 1912-1944 (Polish Edition)
Wiki information Piwnik:
Jan Piwnik was a Polish World War II soldier, a cichociemny and a notable leader of the Home Army in the Świętokrzyskie Mountains. He used the nickname Ponury and Donat.
Barbara Piwnik is a Polish judge. She served as justice minister of Poland from 2001 to 2002.