@book { MathematikfrWirtschaftswissenschaftler,
    title = "Mathematik für Wirtschaftswissenschaftler",
    author = "Michael {Merz} and Mario V. {Wüthrich}",
    year = "2013",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1220875"
}