@misc{Derwich_Marek_(1956–_)_O_1989,
 author={Derwich, Marek (1956– )},
 volume={95},
 editor={Institute of History of the Polish Academy of Sciences},
 number={2},
 copyright={Rights Reserved - Free Access},
 journal={Kwartalnik Historyczny},
 address={Warszawa},
 howpublished={online},
 year={1989},
 publisher={Państwowe Wydawnictwo Naukowe},
 language={pol},
 title={O społeczeństwie Polski średniowiecznej},
 type={Text},
 URL={http://www.rcin.org.pl/Content/22555/PDF/WA303_24520_A52-KH-R-95-2_Derwich.pdf},
 keywords={Poland - Middle Ages, medieval society - Poland},
}