Leaf from a choirbook which had been reused as a cover for a 1596 household account book for the Este family. The leaf, which is still in situ, contains fragments of the Altus and Contratenor parts of the Credo from the Busnoys Missa l'homme armé. This fragment is likely related to MS 221 in the same archive, which contains portions of other voice parts from the Agnus Dei of the same mass.
Discovered by Cristina Solidoro, 2020.