My copy is the first edition published in 1969. (Revised edition is still availabe, I believe.) There's an entry (pp. 177-178) on them. The first paragraph is:
LONZO AND OSCAR: Vocal and instrumental comedy duo, revolving around the Sullivan brothers (1945-'67), both born Edmonton Kentucky, John (Lonzo), born July 7, 1917, died Nashville, Tennessee, June 5, 1967; Rollin (Oscar), born January 19, 1919.
And info on their career and recordings continues. What do you want to know? The whole entry?
~Masato