@book { BetriebsformenwahlltererKonsumentInnen,
    title = "Betriebsformenwahl älterer KonsumentInnen",
    author = "Ernst {Gittenberger}",
    year = "2018",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/b13925",
    url = "https://www.peterlang.com/document/1068475"
}