@book { DiePreisregulierungderBriefdienste,
    title = "Die Preisregulierung der Briefdienste",
    author = "Claudia {Lorentzen}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1090397"
}