@book { Kooperation,
    title = "Kooperation",
    author = "Richard {Balling} and Richard {Balling}",
    year = "1997",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-02229-2",
    url = "https://www.peterlang.com/document/1051864"
}