@book { TheorieentwicklungzurberuflichenSchule,
    title = "Theorieentwicklung zur beruflichen Schule",
    subtitle = "Eine Mehrebenenanalyse",
    author = "Eveline {Wittmann}",
    year = "2009",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1106516"
}