1. Andersen R, Anderson OW:A Decade of Health Services. Chicago, University of Chicago Press, 1967.
2. White EL: A graphic presentation on age and income differentials in selected aspects of morbidity, disability, and utilization of health services.Inquiry 5:18?30, 1968.
3. Research Series;WC Richardson,1971
4. Bergner L, Yerby A: Low income and barriers to use of health services.N Engl J Med 278:541?546, 1968.
5. Aday L: Dimensions of Family's Social Status and Their Relationship to Children's Utilization of Health Services. Unpublished manuscript. Baltimore, Johns Hopkins University Department of Medical Care and Hospitals, 1971.