@book { FokusMittelstand,
    title = "Fokus Mittelstand",
    author = "Christine {Fischer} and Dirk {Nissen} and Ingrid {Ott} and Stephan {Schöning}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1094277"
}