@book { DerAirportNiederrhein,
    title = "Der Airport Niederrhein",
    subtitle = "Potenzialanalyse eines Regionalen Verkehrsflughafens im Marktumfeld der Low Cost-Carrier",
    author = "Markus {Langguth}",
    year = "2006",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    url = "https://m.diplom.de/document/224352"
}