@book { Mittelstandsforschung,
    title = "Mittelstandsforschung",
    author = "Stephan {Schöning} and Ingrid {Ott} and Jörg {Richter} and Dirk {Nissen}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1097378"
}