@book { GrundzgederVolkswirtschaftslehre,
    title = "Grundzüge der Volkswirtschaftslehre",
    author = "Hartwig {Bartling} and Franz {Luzius} and Frank {Fichert}",
    year = "2019",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1221326"
}