@book { FeasibilityStudyandFutureProjectionsofSuborbitalSpaceTourismattheExampleofVirginGalactic,
    title = "Feasibility Study and Future Projections of Suborbital Space Tourism at the Example of Virgin Galactic",
    author = "Matthias {Otto}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836626040",
    url = "https://m.diplom.de/document/226556"
}