@book { PdagogikdesGeistes,
    title = "Pädagogik des Geistes",
    author = "Dietmar {Langer}",
    year = "2012",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-01656-7",
    url = "https://www.peterlang.com/document/1045950"
}