@book { DerVorvertragimInternationalenPrivatrecht,
    title = "Der Vorvertrag im Internationalen Privatrecht",
    author = "Nikolaus {Geiben}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1102890"
}