@Book{OL2982892M,
    title: {Guillaume le Conquérant},
    author: {Michel de Boüard},
    publisher: {Fayard},
    year: {1984},
    place: {[Paris]},
}

@Book{OL21809185M,
    title: {Art d'Occident},
    author: {Henri Focillon},
    publisher: {A. Colin},
    year: {1939},
    place: {Paris},
}

@Book{OL19966886M,
    title: {Gothic architecture and scholasticism},
    author: {Erwin Panofsky},
    publisher: {New American Library},
    year: {1957},
    place: {New York},
}

@Author{OL118686A,
    name: {Erwin Panofsky},
    birth_date: {1892}
    , death_date: {1968}
}