@book { GelegentlicheGedankenberErziehung,
    title = "Gelegentliche Gedanken über Erziehung",
    author = "Johanna {Hopfner}",
    year = "2008",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1104679"
}