@book { MarktgngigeSystemezurPlanungundKontrolle,
    title = "Marktgängige Systeme zur Planung und Kontrolle",
    author = "Thorsten {Jopp}",
    year = "2002",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638133081",
    url = "https://www.hausarbeiten.de/document/5438"
}