Davis, Jeffrey R.; Johnson, Robert; Stepanek, Jan; og Fogarty, Jennifer A. Philadelphia: Lippincott Williams & Wilkins, 2008. Federal Aviation Administration. United States Department of Transportation. FAA-H-8083-11A. Washington, D.C.: U.S. Government Printing Office, 2007. Glenday, Craig. New York: Bantam Books, 2011. Linjal, John og Phillips, Laurence. Chalfont St Peter, Bucks: Bradt Travel Guides, 2010. Shectman, Jonathan. Westport, Connecticut.: Greenwood Press, 2003.