@misc{_Zum_1889,
 address={St. Petersburg},
 howpublished={online},
 year={1889},
 publisher={Kaiserlichen Akademie der Wissenschaften},
 language={ger},
 title={Zum 50-Jährigen Bestehn der Nicolai-Hauptsternwarte},
 keywords={Pulkova Observatory, history of Pulkova Observatory},
}