@book { AlternativesozialeSicherungssysteme,
    title = "Alternative soziale Sicherungssysteme",
    author = "Christian {Buschbeck}",
    year = "1999",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832419882",
    url = "https://m.diplom.de/document/217831"
}