Eustachio Romano, Musica duorum: Liber primus (Giovanni Giacomo Pasotti, Rome 1521).

info       title page

45 textless duos. There is one book only with the two voices printed on the same opening: on the left the upper voice, on the right the lower one.

While the progressive letters concerning the duos are found on the music page, all the rubrics concerning the voices are found in the Tavola only.