@book { ServicequalittamPOS,
    title = "Servicequalität am POS",
    author = "Annika {Lehnert}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836632515",
    url = "https://m.diplom.de/document/227024"
}