@book { TennisEdelsportfrdasVolk,
    title = "Tennis - Edelsport für das Volk?",
    subtitle = "Eine telefonische Befragung zur Imageanalyse des Tennissports in der Stadt München",
    author = "Martin {Schmid}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    url = "https://m.diplom.de/document/227291"
}