U.S. Food and Drug Administration.  Center for Food Safety and Applied Nutrition.  Dietary Supplement Sales Database (DSPD) [Data file], prepared by Research Triangle Institute.  October 1999.  Research Triangle Park, NC:  Research Triangle Institute.  College Park, MD: FoodRisk.org [Distributor]. Available at: http://www.foodrisk.org/exclusives/DSPD/

U.S. Food and Drug Administration.  Center for Food Safety and Applied Nutrition.  Dietary Supplement Sales Information:  Contract No. 223-96-2290:  Task Order 4:  Final Report [Online], prepared by Mary K. Muth, et al., Research Triangle Institute, Center for Economics Research.  October 1999. Research Triangle Park, NC:  Research Triangle Institute.  College Park, MD: FoodRisk.org [Distributor]. Available at: http://www.foodrisk.org/exclusives/DSPD/downloads/DietSup_6673_4_FR.pdf

U.S. Food and Drug Administration.  Center for Food Safety and Applied Nutrition.  Dietary Supplement Sales Information:  Contract No. 223-96-2290:  Task Order 4:  Supplement to the Final Report [Online], prepared by Mary K. Muth, Jean L. Domanico, and Peter H. Siegel, Research Triangle Institute, Center for Economics Research.  October 1999. Research Triangle Park, NC:  Research Triangle Institute.  College Park, MD: FoodRisk.org [Distributor]. Available at: http://www.foodrisk.org/exclusives/DSPD/downloads/DietSup_6673_4_FR_Sup.pdf