Kopardekar, P. H., A. Schwartz, S. Magyarits, and J. Rhodes. “Airspace Complexity Measurement: An Air Traffic Control Simulation Analysis”. International Journal of Industrial Engineering: Theory, Applications and Practice, vol. 16, no. 1, Mar. 2009, pp. 61-70, doi:10.23055/ijietap.2009.16.1.18.