Three

It turns out there are three basic collections of readings still extant in the West:

I. Würzburg (6th century, Gelasian)

II. Alcuin (7th century, Gregorian)

III. Murbach (8th century, Gelasian)

The last is the source of the medieval lectionary used by Anglicans and Lutherans. But what is the source of the lectionary of the Tridentine missal (1570)? It isn't the first: it is the second, which Tommasi rendered, from words found in the preface, as Comes ab Albino.

Peruse its fragile pages here.