@book { DieUrsulinenschuleinKoblenz19021950,
    title = "Die Ursulinenschule in Koblenz 1902–1950",
    author = "Rudolf {Feld}",
    year = "2014",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-05030-1",
    url = "https://www.peterlang.com/document/1050437"
}