@book { DasPhnomenFreiwilligkeitinNonprofitOrganisationen,
    title = "Das Phänomen „Freiwilligkeit“ in Nonprofit-Organisationen",
    author = "Ulrike {Kogler}",
    year = "2009",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640279579",
    url = "https://www.hausarbeiten.de/document/122957"
}