@book { SpringkleineLulu,
    title = "Spring, kleine Lulu!",
    subtitle = "Die schönsten Pferdegeschichten",
    author = "Natascha {Becker}",
    year = "2016",
    publisher = "jumpbooks",
    address = "München, Deutschland",
    url = "https://www.jumpbooks.de/document/318469"
}