1. Bureau of the Census 1971. 1967 Census of manufac-turers. vol. 3, part 1. Washington, D. C.: U. S. Dept. of Commerce.
2. Bureau of the Census 1973. 1970 Census of popula-tion: Characteristics of the population. vol. 1, part 15. Washington, D. C.: U. S. Dept. of Com-merce.
3. Bureau of the Census 1981. 1977 Census of manufac-turers. vol. 3, part 1. Washington, D. C.: U. S. Dept. of Commerce.
4. Bureau of the Census 1982. 1980 Census of popula-tion: General population characteristics, Illinois. Washington, D. C.: U. S. Dept. of Commerce.
5. Bureau of the Census 1985. 1982 Census of manufac-turers: Geographic area series, Illinois. Washing-ton, D. C.: U. S. Dept. of Commerce.