@misc{Spangenberg_Hans_(1868-1936)_Die,
 author={Spangenberg, Hans (1868-1936)},
 howpublished={online},
 publisher={[R. Oldenbourg]},
 language={ger},
 type={książka},
 title={Die Perioden der Weltgeschichte},
 keywords={historia, periodyzacja},
}