@book { PositionierungvonDienstleistungen,
    title = "Positionierung von Dienstleistungen",
    author = "Matthias C. {Weber}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832434809",
    url = "https://m.diplom.de/document/219146"
}