@book { DasLeanKonzept,
    title = "Das Lean-Konzept",
    author = "Heiko {Nett}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832437220",
    url = "https://m.diplom.de/document/219407"
}