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Bibliotèque cantonale jurassienne, MS 18, Porrentruy, Switzerland (12th century), Gradual used by the Prémontré order at the Abbey of Bellelay; showing staves with C clefs (Gradual for 3rd Mass of Christmas, Viderunt omnes) |
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Bibliotèque cantonale jurassienne, MS 18, Porrentruy, Switzerland (12th century), Gradual used by the Prémontré order at the Abbey of Bellelay; showing staves with C clefs (Gradual for 3rd Mass of Christmas, Viderunt omnes) |