@misc{Langerówna_Helena_System,
 author={Langerówna, Helena},
 howpublished={online},
 publisher={Gebethner i Wolff},
 language={Polish},
 title={System obronny Doliny Dunajca w XIV w.},
 type={book},
 keywords={Poland, history, defensive architecture, Polish architecture, Dunajec (river), fortresses and fortifications, catchments and river basins},
}