@misc{Opli_Ferdinand_Cologne_2005,
 author={Opli, Ferdinand},
 volume={92},
 editor={Institute of History of the Polish Academy of Sciences},
 copyright={Rights Reserved - Restricted Access},
 address={Warszawa},
 journal={Acta Poloniae Historica},
 howpublished={online},
 year={2005},
 publisher={Wydawnictwo Naukowe Semper},
 language={eng},
 type={Text},
 title={Cologne and Vienna in the Middle Ages: a Comparison},
 keywords={Köln (Germany), Wien (Austria), Middle Ages, towns},
}