1. Standard Industrial Classification Manual;U.S. Executive Office of the President. Office of Management Budget,1972
2. The pluralistic economy of the U.S.;Ginzberg;Scientific American,1976
3. Good Jobs, Bad Jobs, No Jobs;Ginzberg,1979
4. The service sector of the U.S. economy;Ginzberg;Scientific American,1981
5. The Service Economy;Fuchs,1968