@book { FreeandUnfreeLabour,
    title = "Free and Unfree Labour",
    subtitle = "The Debate Continues",
    author = "Tom {Brass} and Marcel van der {Linden}",
    year = "1997",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1087557"
}