@book { DiePISAStudie,
    title = "Die PISA-Studie",
    author = "Maike {Wörsching}",
    year = "2005",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638347914",
    url = "https://www.hausarbeiten.de/document/34620"
}