@book { DasInHouseGeschftimEGVergaberecht,
    title = "Das In-House Geschäft im EG-Vergaberecht",
    author = "Alexander Nicolas {Wittek}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1098202"
}