@misc{_500th,
 address={[s.l.]},
 howpublished={online},
 publisher={[s.n.]},
 language={pol},
 type={druk},
 title={500th anniversary of Nicolaus Copernicus : february 19, 1473-1973: 1923 Poland Issued to Commemorate, 450th Anniversary of Nicolaus Copernicus Polish Astronomer},
 keywords={Kopernik, Mikołaj (1473-1543)},
}