@misc{Kepler_Johannes_Joannis_1863,
 author={Kepler, Johannes},
 address={Frankofurti a. M. et Erlangae},
 howpublished={online},
 year={1863},
 publisher={Heyder and Zimmer},
 language={lat},
 title={Joannis Kepleri Astronomi Opera Omnia. Vol. IV},
 type={text},
 keywords={Gregorian calendar, Kepler's chronology},
}