@book { QualittsmerkmalBeziehung,
    title = "Qualitätsmerkmal Beziehung",
    author = "Rainer {Klein} and Monika {Hammerla-Claassen}",
    year = "2021",
    publisher = "Schlütersche Verlagsgesellschaft mbH & Co. KG",
    address = ", Deutschland",
    url = "https://schluetersche.openpublishing.com/document/993681"
}