@book { CoVis3,
    title = "CoVis 3",
    subtitle = "Visual Representaion of three-dimensional Data and Functions of two Variables",
    author = "Danyel {Merkert}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832456313",
    url = "https://m.diplom.de/document/221111"
}