Copyright Text: Daniels, D.L., Kucks, R.P., Hill, P.L. (2012). Illinois, Indiana, and Ohio Magnetic and Gravity Maps and Data: A Website for Distribution of Data [Data Set](321). USGS Data Series. United States Geological Survey. http://gis.utep.edu/rgsc/index.php?option=com_content&view=article&id=45&Itemid=54