@book { DasCausaproblemimdeutschenBereicherungsrecht,
    title = "Das Causaproblem im deutschen Bereicherungsrecht",
    author = "Guangyu {Fu}",
    year = "2011",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-00444-1",
    url = "https://www.peterlang.com/document/1044391"
}