@book { ServiceMarketingInnovationssomegeneralconcepts,
    title = "Service Marketing Innovations - some general concepts",
    author = "Yasemin {Sari}",
    year = "2011",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640798704",
    url = "https://www.hausarbeiten.de/document/164261"
}