Ottaviano Petrucci: Canti B Numero Cinquanta (Venice, 1502). Ed. Helen Hewitt, introd. Edward E. Lowinsky. Texts ed. and annotated by Morton W. Briggs, tr. Norman B. Spector. (Monuments of Renaissance Music, Vol. 11.) Chicago: Chicago University Press, 1967. xx+ 242 pp. $32.50