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William F. Fox (March 13, 2002). "History and Economic Impact: Sales Tax History"(PDF). University of Tennessee Knoxville, Center for Business and Economic Research. Archived from the original(PDF) on April 30, 2011. Retrieved April 15, 2011.
"Value added tax". Government Spokesperson’s Office, Principality of Liechtenstein. Archived from the original on April 18, 2005. Retrieved April 14, 2011.
Laurence J. Kotlikoff (March 7, 2005). "The Case for the 'FairTax'"(PDF). The Wall Street Journal. p. A18. Archived from the original(PDF) on November 13, 2018. Retrieved April 14, 2011.
William F. Fox (March 13, 2002). "History and Economic Impact: Sales Tax History"(PDF). University of Tennessee Knoxville, Center for Business and Economic Research. Archived from the original(PDF) on April 30, 2011. Retrieved April 15, 2011.