Source: OxfB Add. C. 87*, fols. 225r-226v. Edition: Ernst Apfel, Studien zur Satztechnik der mittelalterlichen englischen Musik, 2 vols. (Heidelberg: Carl Winter, 1959), 2: 142-45. See also Gareth Curtis, ed., Fifteenth-Century Liturgical Music IV: Early Masses and Mass-Pairs, Early English Church Music, 42 (London: Stainer and Bell for The British Academy, 2001), 14-29, for what remains of the Gloria and Sanctus. Wegman's title seems to suggest that this is a cantus firmus mass based on the chant "Requiem eternam" but NOT a Requiem mass itself. Totally uncertain of date. Only Credo survives in its entirety.