@book { DerGeistderFreude,
    title = "Der Geist der Freude",
    author = "Jochen {Bertheau}",
    year = "2012",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-02472-2",
    url = "https://www.peterlang.com/document/1046464"
}