@book { DasBereicherungsverbotimVertragsrecht,
    title = "Das Bereicherungsverbot im Vertragsrecht",
    author = "Patrick {Wersin}",
    year = "2019",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/b15855",
    url = "https://www.peterlang.com/document/1057835"
}