Digest of Education Statistics. Washington, D.C.: U.S. Department of Health, Education, and Welfare, Education Division, National Center for Education Statistics, 1976 - , Edu. Ref. L11.D48
Projections of Education statistics to ... Washington: U.S.: Department of Health, Education, and Welfare, Office of Education, 1964- , Edu. Ref. LA210.A28
National Center for Education Statistics (NCES), below: