@book { DieBuchpreisbindunginderEWG,
    title = "Die Buchpreisbindung in der EWG",
    author = "Heike {Langbein}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1076990"
}