@book { DerFreiverkehr,
    title = "Der Freiverkehr",
    author = "Karsten {Fink}",
    year = "2013",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-03496-7",
    url = "https://www.peterlang.com/document/1046578"
}