@book { PublicRelationsinmittelstndischenUnternehmen,
    title = "Public Relations in mittelständischen Unternehmen",
    author = "Silke {Balsys}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832470869",
    url = "https://m.diplom.de/document/222405"
}