@book { SpringkleineLulu,
    title = "Spring, kleine Lulu!",
    author = "Natascha {Becker}",
    year = "2012",
    publisher = "dotbooks Verlag",
    address = "München, Deutschland",
    doi = "10.3239/9783943835960",
    url = "https://m.dotbooks.de/document/199282"
}