@Book{OL24088724M,
    title: {Debt},
    author: {David Graeber},
    publisher: {Melville House},
    year: {2011},
    place: {Brooklyn, New York, USA},
}

@Book{OL6317209M,
    title: {The state in theory and practice},
    author: {Harold Joseph Laski},
    publisher: {The Viking Press},
    year: {1935},
    place: {New York},
}

@Book{OL6936991M,
    title: {Wage-labor and capital},
    author: {Karl Marx and Friedrich Engels},
    publisher: {New York Labor News Co.},
    year: {1902},
    place: {New York},
}

@Author{OL48230A,
    name: {Karl Marx},
    birth_date: {5 May 1818}
    , death_date: {14 March 1883}
}
@Author{OL1368A,
    name: {Friedrich Engels},
    birth_date: {28 November 1820}
    , death_date: {5 August 1895}
}