Complex sentence: Goldman researched "Butch Cassidy and the Sundance Kid" for eight years, and used Harry Longbaugh (a variant spelling of the Sundance Kid's real name) as his pseudonym for "No Way to Treat a Lady".
Split into simpler sentences: Goldman researched "Butch Cassidy and the Sundance Kid" for eight years. He used Harry Longbaugh (a variant spelling of the Sundance Kid's real name) as his pen name for "No Way to Treat a Lady".