Jo Stafford was a vocalist whose sweet timbre helped to define popular music from World War II through the 1950s.Associated Press: Singer and radio star Jo Stafford dies at 90 (July 19, 2008) She sold over 25 million records and worked with such icons as Tommy Dorsey, Rosemary Clooney, Frank Sinatra, Johnny Mercer and Perry Como.CNN.com: Big-band singer Jo Stafford dead at 90 (July 19, 2008) Stafford died on July 17, 2008, of congestive heart failure.