@book { TheorienderSozialenArbeitSystemtheorie,
    title = "Theorien der Sozialen Arbeit: Systemtheorie",
    author = "Ramona {Schwartz}",
    year = "2009",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640472178",
    url = "https://www.hausarbeiten.de/document/138025"
}