Complex sentence: He attended Louisiana State University (B.M., 1947) where he was a pupil of Helen Gunderson and the Eastman School of Music (M.M., 1949) where he studied with Bernard Rogers and Howard Hanson.
Split into simpler sentences: He attended Louisiana State University (B.M., 1947) where he was a pupil of Helen Gunderson. He also attended the Eastman School of Music (M.M., 1949) where he studied with Bernard Rogers and Howard Hanson.