@book { QualitativeundquantitativeMethoden,
    title = "Qualitative und quantitative Methoden",
    author = "Pamela {Bastuck}",
    year = "2009",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640243327",
    url = "https://www.hausarbeiten.de/document/120762"
}