Iowa Department of Transportation, 2004 Geographic Information Systems Statewide and County Data Archived 2007-08-17 at the Wayback Machine Illinois Department of Transportation, 2004 GIS Data "Indiana Highway Ends - US 30".
2014년 10월 9일에 확인함.  Iowa Department of Transportation, 2004 Geographic Information Systems Statewide and County Data Archived 2007년 8월 17일 - 웨이백 머신 Illinois Department of Transportation, 2004 GIS Data “Indiana Highway Ends - US 30”.