@book { DerVertragmitSchutzwirkungfrDritte,
    title = "Der Vertrag mit Schutzwirkung für Dritte",
    author = "Anna {Ziegltrum}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1113617"
}