@book { WarumundwieermordetedieGPULeoTrotzki,
    title = "Warum und wie ermordete die GPU Leo Trotzki?",
    author = "Peter {Schwarz}",
    year = "2016",
    publisher = "MEHRING Verlag",
    address = "Essen, Deutschland",
    url = "https://mehring.openpublishing.com/document/324360"
}