@book { YieldManagementimTourismus,
    title = "Yield Management im Tourismus",
    author = "Bernd {Kerbl}",
    year = "2009",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640357321",
    url = "https://www.hausarbeiten.de/document/132034"
}