@book { Superlernen,
    title = "Super lernen",
    subtitle = "Tipps & Tricks von A-Z   Effektiver Lernen   Mit vielen Übungen",
    author = "Ursula {Oppolzer}",
    year = "2010",
    publisher = "humboldt",
    address = "Hannover, Deutschland",
    url = "https://schluetersche.openpublishing.com/document/403442"
}