Complex sentence: Norman sold the station to Doubleday Broadcasting in 1976 who changed the station's call letters to WWWK (later KWK-FM) and the format to Top 40.
Split into simpler sentences: Norman sold the station to Doubleday Broadcasting in 1976. Doubleday changed the station's call letters to WWWK (later KWK-FM) and the format to Top 40.