@book { ErfolgsfaktorendesMarketing,
    title = "Erfolgsfaktoren des Marketing",
    author = "Katja {Gelbrich} and Stefan {Müller}",
    year = "2024",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1478420"
}