Agnus available on Wegman site as .mp3; missing from package sent.
Source: SienBC K.I.2, fols. 168v-182r (1490s).
Edition: Timothy J. Dickey, Reading the Siena Choirbook: A Re-appraisal of the Dating, Musical Repertories, And Marian Performance Context of the Manuscript Siena, Biblioteca Comunale degli Intronati, MS. K.1.2 (Ph.D. diss., Duke University, 2003), 405-27.