@online{ timsrc, author = "Kley, Wilhelm AND Werner, Klaus", title = "Streifzug durch die Astronomie, 21. und 22. Stunde", publisher = "Universität Tübingen", year = "2017", month = "Jan", day = "17", url = "https://timms.uni-tuebingen.de:443/tp/UT_20170117_001_rvastro_0001", urldate = "2024-12-04" }