@online{ timsrc, author = "Kley, Wilhelm AND Werner, Klaus", title = "Streifzug durch die Astronomie, 17. und 18. Stunde", publisher = "Universität Tübingen", year = "2016", month = "Dec", day = "20", url = "https://timms.uni-tuebingen.de:443/tp/UT_20161220_001_rvastro_0001", urldate = "2024-12-22" }