@book { Seniorenaktivierungkompakt,
    title = "Seniorenaktivierung kompakt",
    author = "Monika {Hammerla} and Claudia {Keller}",
    year = "2012",
    publisher = "Schlütersche Verlagsgesellschaft mbH & Co. KG",
    address = ", Deutschland",
    url = "https://schluetersche.openpublishing.com/document/403778"
}