A GUIDE TO OPERA RECORDINGS. By Ethan Mordden. 308 pp. New York: Oxford University Press. $24.95
New Sounds. By John Schaefer. 297 pp. New York: Harper and Row, 1987. $22.95 cloth, $10.95 paper
DUKE ELLINGTON. By James Lincoln Collier. 340 pp. (illustrated). New York: Oxford University Press, 1987. $19.95