@book { DasgroeBrainFitnessBuch,
    title = "Das große Brain-Fitness-Buch",
    author = "Ursula {Oppolzer}",
    year = "2010",
    publisher = "humboldt",
    address = "Hannover, Deutschland",
    url = "https://schluetersche.openpublishing.com/document/403413"
}