@book { GrundlagenderWillenspdagogik,
    title = "Grundlagen der Willenspädagogik",
    author = "Dietmar {Langer}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1105417"
}