@online{
   timsrc,
   author = "Werner, Klaus",
   title = "Vorlesung Einführung in die Astronomie II, 3. Stunde",
   publisher = "Universität Tübingen",
   year = "2009",
   month = "May",
   day = "06",
   url = "https://timms.uni-tuebingen.de:443/tp/UT_20090506_001_astro2_0001",
   urldate = "2024-04-20"
}