@book { DerVerkaufunterEinstandspreisnach20Abs4Satz2GWB,
    title = "Der Verkauf unter Einstandspreis nach § 20 Abs. 4 Satz 2 GWB",
    author = "Dietrich {Kamlah}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1094219"
}