@book { PropertyInvestmentinBulgaria,
    title = "Property Investment in Bulgaria",
    subtitle = "Why invest? Why not to invest?",
    author = "Jubilee Jenna {Mandl}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836605847",
    url = "https://m.diplom.de/document/225391"
}