Complex sentence: He later helped Spitzer edit "The Gestalt Approach" (1973), based on a manuscript by gestalt therapist Fritz Perls, who had recently died; he also assisted with checking transcripts for "Eye Witness to Therapy" (1973).
Split into simpler sentences: He later helped Spitzer edit "The Gestalt Approach" (1973) based on a manuscript by gestalt therapist Fritz Perls who had recently died. He also assisted with checking transcripts for "Eye Witness to Therapy" (1973).