@book { DieBedeutungdesArt19Einigungsvertrag,
    title = "Die Bedeutung des Art. 19 Einigungsvertrag",
    author = "Hartmut {Breuer}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1088028"
}