@book { KooperationsalternativenimMittelstand,
    title = "Kooperationsalternativen im Mittelstand",
    author = "Benjamin {Trümpler}",
    year = "2004",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638303552",
    url = "https://www.hausarbeiten.de/document/28625"
}