@misc{_Polskie_[1939?],
 copyright={Public Domain},
 address={[S.l.]},
 howpublished={online},
 year={[1939?]},
 publisher={[s.n.]},
 language={pol},
 type={Image},
 title={Polskie Zagłębie Węglowe : 1:400 000},
 keywords={economic maps, coal mining, Upper Silesian Industrial Region},
}