@book { Anempiricalinvestigationofsupermarketdifferentiation,
    title = "An empirical investigation of supermarket differentiation",
    author = "Cornelia {Obitz}",
    year = "2008",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836619639",
    url = "https://m.diplom.de/document/226162"
}