@book { TourismusundFreizeitimHochschwarzwald,
    title = "Tourismus und Freizeit im Hochschwarzwald",
    author = "Matthias {Schopp}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836604963",
    url = "https://m.diplom.de/document/228985"
}