@book { konomischeGeographie,
    title = "Ökonomische Geographie",
    author = "Johannes {Bröcker} and Johannes {Bröcker} and Michael {Fritsch} and Michael {Fritsch} and Hayo {Herrmann} and Helmut {Karl} and Gerhard {Kempkes} and Gabriel {Lee} and Joachim {Möller} and Helmut {Seitz}",
    year = "2020",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1219136"
}