APA (7th ed.) Citation

Geological Survey (U.S.). (1992). State of Illinois [planimetric]: Base map with highways (Ed. of 1987.). The Survey.

Chicago Style (17th ed.) Citation

Geological Survey (U.S.). State of Illinois [planimetric]: Base Map with Highways. Ed. of 1987. Reston, Va.: The Survey, 1992.

MLA (9th ed.) Citation

Geological Survey (U.S.). State of Illinois [planimetric]: Base Map with Highways. Ed. of 1987. The Survey, 1992.