@misc{_Polski_[ca,
 editor={Ewig, F. Oprac.},
 copyright={Rights Reserved - Restricted Access},
 address={Drohobycz},
 howpublished={online},
 year={[ca 1930]},
 publisher={F. Ewig},
 language={pol},
 language={fre},
 language={ger},
 title={Polski obszar naftowy = Territoire de pétrole polonais = Das Polnische Naphtagebiet},
 keywords={economic maps, crude oil mining, Poland, Ukraine},
}