@book { FreizeitundSeniorenanimation,
    title = "Freizeit- und Seniorenanimation",
    author = "Franz J. M. {Mayr}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1092490"
}