@book { LeadUserundihrPotentialfrUnternehmen,
    title = "Lead User und ihr Potential für Unternehmen",
    author = "Ursula {Hertlein}",
    year = "2006",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638551793",
    url = "https://www.hausarbeiten.de/document/61810"
}