@book { berdieSpingruppeeinespseudoeuklidischenVektorraumes,
    title = "Über die Spingruppe eines pseudoeuklidischen Vektorraumes",
    author = "Yuliya {Schumacher}",
    year = "2008",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836616614",
    url = "https://m.diplom.de/document/225989"
}