Author & Contributor Index
- Illinois. Institute for Social Policy
- Illinois Institute of Natural Resources
- Illinois Institute of Natural Resources, State Water Survey Division
- Illinois Institute of Technology
- Illinois International High School Initiative
- Illinois. Interstate Oil Compact Commission
- Illinois. Lake Michigan Coast and Basin Studies
- Illinois. Land Reclamation Division
- Illinois Master Plumbers' Association
- Illinois Mineral Industries Committee
- Illinois Mine Subsidence Insurance Fund
- Illinois Mine Subsidence Research Program
- Illinois Museum of Natural History
- Illinois. National History Survey Division
- Illinois Natural History Society,
- Illinois Natural History Survey
- Illinois Natural History Survey,
- Illinois. Natural History Survey. Center for Biodiversity
- Illinois Natural History Survey Division
- Illinois. Natural History Survey Division. Aquatic Biology Section
- Illinois. Natural History Survey Division. Center for Aquatic Biology
- Illinois. Natural History Survey Division. Center for Biodiversity
- Illinois. Natural History Survey Division. Center for Biogeographic Information
- Illinois. Natural History Survey Division. Center for Wildlife Ecology
- Illinois. Natural History Survey Division. Division of Fisheries
- Illinois. Natural History Survey Division. Economic Entomology Section
- Illinois. Natural History Survey Division. Lake Michigan Biological Station
- Illinois. Natural History Survey Division. LTRMP Havana Field Station
- Illinois. Natural History Survey Division. River Research Laboratory
- Illinois Nature Preserves Commission
- Illinois. Office of Capital Development/Engineering
- Illinois. Office of Solid Waste and Renewable Resources
- Illinois Office of Water Resources
- Illinois River Strategy Team
- Illinois Secondary School Principals' Association. Curriculum Committee. Junior-College Committee
- Illinois. Section of Faunistic Surveys and Insect Identification
- Illinois. Section of Wildlife Research
- Illinois Specialty Growers Association
- Illinois State Academy of Science
- Illinois State Archaeological Survey
- Illinois State Department of Public Health
- Illinois State Department of Public Health and the University of Illinois
- Illinois State Department of Public Health Division of Sanitary Engineering and the University of Illinois Department of Civil Engineering
- Illinois State Entomologist,
- Illinois. State Entomologist
- Illinois State Geological Survey
- Illinois State Geological Survey Coal Section
- Illinois State Geological Survey. Hydrogeology and Geophysics Section
- Illinois State Geological Survey. Wetlands Geology Section
- Illinois State Horticultural Society