1. United States Department of Agriculture. National Survey on Recreation and Environment. Available at: http://www.srs.fs.usda.gov/trends/Nsre/nsre2.html. Accessed July 5, 2008.
2. Projection of outdoor recreation participation to 2050;Bowker,1999
3. National Park Service. Shenandoah National Park. Available at: http://www.nps.gov/shen/parkmgmt/statistics.htm. Accessed July 5, 2008.
4. U.S. News and World Report. Hospital directory search. Available at: http://health.usnews.com/directories/hospital-directory/index_html. Accessed July 5, 2008.
5. Healthcare needs of Appalachian Trail hikers;Crouse;J Fam Pract,1993