@book { LoyaltySchemesinRetailing,
    title = "Loyalty Schemes in Retailing",
    author = "Nicolas {Hoffmann}",
    year = "2013",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-03515-5",
    url = "https://www.peterlang.com/document/1067470"
}