@misc{Ptaśnik_Jan_(1876–1930)_Denar_1908,
 author={Ptaśnik, Jan (1876–1930)},
 copyright={Public Domain},
 address={Kraków},
 howpublished={online},
 year={1908},
 publisher={AU},
 language={pol},
 title={Denar świętego Piotra obrońcą jedności politycznej i kościelnej w Polsce},
 URL={http://www.rcin.org.pl/iae/Content/4814/PDF/WA308_581_II15837_DENAR-SWIETEGO_I.pdf},
 keywords={10th-14th c.-- Poland, papacy and Poland in the Middle Ages, Peter's Pence in the Middle Ages},
}