APA (7th ed.) Citation

Geological Survey (U.S.). (1975). Index map of Illinois showing availabilty of flood-prone area maps (July 1975.). Geological Survey.

Chicago Style (17th ed.) Citation

Geological Survey (U.S.). Index Map of Illinois Showing Availabilty of Flood-prone Area Maps. July 1975. Champaign, Il: Geological Survey, 1975.

MLA (9th ed.) Citation

Geological Survey (U.S.). Index Map of Illinois Showing Availabilty of Flood-prone Area Maps. July 1975. Geological Survey, 1975.