@book { EineansichmittelmigeFrage,
    title = "Eine an sich mittelmäßige Frage",
    author = "Karl-Otto {Hagelstein}",
    year = "2012",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-01516-4",
    url = "https://www.peterlang.com/document/1045995"
}