1. Airport-Technology.com, 2009. O׳Hare International Airport (ORD/KORD), Chicago, IL, USA. 〈www.airport-technology.com/projects/chicago〉 (cited 26.05.09).
2. ATCMonitor.com, 2006. Atlanta Airports Expansion, Building a New Level of Capacity: Runway 10/28, Control Tower, East Terminal. 〈www.atcmonitor.com/atlexpansion.html〉 (cited 26.05.09).
3. Belobaba P.P., 2006. Operating Costs and Productivity Measures. Course 16.75J/1.234J Airline Management. Massachusetts Institute of Technology, Cambridge MA, USA. 〈http://ocw.mit.edu/OcwWeb/Aeronautics-and-Astronautics/16-75JSpring-2006/CourseHome/index.htm〉.
4. Belobaba, P., 2008. Chapter 3: Overview of Airline Economics, Markets and Demand. Course 16.75J/1.234J Airline Management. Massachusetts Institute of Technology, Cambridge, MA, USA. 〈http://ocw.mit.edu/OcwWeb/Aeronautics-and-Astronautics/16-75JSpring-2006/CourseHome/index.htm〉.
5. CCSP (US Climate Change Science Program), 2007. Scenarios of Greenhouse Gas Emissions and Atmospheric Concentrations. 〈http://www.climatescience.gov/Library/sap/sap2-1/finalreport/sap2-1a-final-all.pdf〉 (cited 27.06.08).