@book { UnterrichtausderSichtvonHandelslehrern,
    title = "Unterricht aus der Sicht von Handelslehrern",
    author = "Jürgen {Seifried}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1106519"
}