1. World Tourism Organization. Tourism 2020 vision. Available at: http://www.world-tourism.org. (Accessed 2008 Jun 18)
2. Travel Industry Association. Travel market segments. Available at: http://www.tia.org/researchpubs/travel_market_segments.html. (Accessed 2008 Jun 18)
3. Etiology of travel-related fever
4. Reemerging Leptospirosis, California
5. Leptospirosis in Germany, 1962–2003