@book { DasGeheimnisdesSchmetterlings,
    title = "Das Geheimnis des Schmetterlings",
    subtitle = "Roman",
    author = "Constanze {Wilken}",
    year = "2016",
    publisher = "dotbooks Verlag",
    address = "München, Deutschland",
    url = "https://www.dotbooks.de/document/340914"
}