@book { LineareSystemeinderWirtschaft,
    title = "Lineare Systeme in der Wirtschaft",
    subtitle = "Lineare Algebra, Lineare Optimierung",
    author = "Emil {Larek}",
    year = "2014",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1109557"
}