Complex sentence: In 1930 he guest-conducted with the San Francisco Symphony, and was later invited to become its music director, where from 1930 and 1932 he served as joint music director with Issay Dobrowen.
Split into simpler sentences: In 1930 he guest-conducted with the San Francisco Symphony, and was later invited to become its music director. Between 1930 and 1932 he served as joint music director with Issay Dobrowen.