@book { DirectBankingimVertriebssystemvonKreditgenossenschaften,
    title = "Direct Banking im Vertriebssystem von Kreditgenossenschaften",
    author = "Christian {Heigl}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1090655"
}