@book { MusikalischesDenkenimMittelalter,
    title = "Musikalisches Denken im Mittelalter",
    subtitle = "Eine Einführung",
    author = "Max {Haas}",
    year = "2007",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1102308"
}