Complex sentence: He engineered Bruno Walter's cycle of the nine Beethoven symphonies with the Columbia Symphony Orchestra, over thirty recordings with Igor Stravinsky, and around three hundred with Leonard Bernstein.
Split into simpler sentences: He engineered Bruno Walter's cycle of the nine Beethoven symphonies with the Columbia Symphony Orchestra. He also worked on over thirty recordings with Igor Stravinsky, and around 200 with Leonard Bernstein.