@book { MarketingOptionsoftheNationalBloodService,
    title = "Marketing Options of the National Blood Service",
    author = "Christopher {Ulph}",
    year = "2011",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640819577",
    url = "https://www.hausarbeiten.de/document/166059"
}