@book { DieallgemeineUmweltnutzungsfreiheit,
    title = "Die allgemeine Umweltnutzungsfreiheit",
    author = "Frank {Haddenhorst}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1092234"
}