@book { DieUnterrichtsformen,
    title = "Die Unterrichtsformen",
    subtitle = "Eine problemgeschichtliche Studie",
    author = "Günter {Scholz}",
    year = "2005",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1099957"
}