Analysis, US Department of Commerce, BEA, Bureau of Economic. "Bureau of Economic Analysis". www.bea.gov. Retrieved April 10, 2018.{{cite web}}: CS1 maint: multiple names: authors list (link)
Menendez, Albert J. (2005). The Geography of Presidential Elections in the United States, 1868-2004. London: Jefferson: McFarland & Company. pp. 284–285. ISBN0786422173. OCLC750587959.