1. FAA, "Airport and air traffic control system, Airport and air traffic control system".
2. J. Wilson, "Quora," [Online]. Available: https://www.quora.com/How-many-airports-are-there-in-the-world-1.
3. J. Gibson, "Airport and Air Traffic Control System," 1982.
4. Worldfinance, "Worldfinance," [Online]. Available: https://www.worldfinance.com/markets/the-worlds-five-fastest-growing-economies.
5. P. Senguttuvan, "Economics of the Airport CApacity System in the Growing Demand of Air Traffic," New York, 2006.