@misc{_Ost,
 address={[Wien]},
 howpublished={online},
 publisher={[s.n.]},
 language={ger},
 type={mapa},
 title={Ost Preusen : I BL N 73; II BL N 74; III BL N 75; V BL N 77},
 keywords={Polska -- mapy -- 18 w, Prusy Wschodnie -- 18 w},
}