1. 1. National Data Book and Guide to Sources (1988 ) Statistical Abstract of the United States (108th ed. ) p.25 .U.S. Department of Commerce.
2. 2. U.S. Department of Health and Human Services (1988 ) Surgeon General's Report on Nutrition and Health , pp.1 -17 . Public Health Service. DHHS (PHS) publication no. 88-50211. U.S. Government Printing Office. Washington, D.C.