Appraisal Institute http://www.appraisalinstitute.org/ Polk County Assessor http://www.assess.co.polk.ia.us/index.html Dallas County Assessor https://beacon.schneidercorp.com/?site=DallasCountyIA Warren County Assessor https://beacon.schneidercorp.com/?site=WarrenCountyIA U.S. Department of Labor-CPI Factors http://www.bls.gov/cpi/ Iowa Geographic Map Server GIS ISU http://ortho.gis.iastate.edu/