@book { DasKitaGutscheinsystemHamburgs,
    title = "Das Kita-Gutscheinsystem Hamburgs",
    author = "David {Liebelt}",
    year = "2008",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640113125",
    url = "https://www.hausarbeiten.de/document/112654"
}