@book { TourismusundNaturschutz,
    title = "Tourismus und Naturschutz",
    author = "Karsten {Heinsohn}",
    year = "2005",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832485269",
    url = "https://m.diplom.de/document/223730"
}