1. American airlines seeks to cancel labor contracts;Associated Press,2012
2. Parametric efficiency tests, economies of scale and input demand in US electric power generation;Atkinson;International Economic Review,1984
3. Transportation deregulation: productivity and cost patterns in trucking, airlines and rail;Bitzan,2014
4. Airline deregulation: the cost pieces of the puzzle;Baltagi;International Economic Review,1995
5. Bureau of Labor Statistics, http://www.bls.gov/ooh/transportation-and-material-moving/airline-and-commercial-pilots.htm (BLS, 2012).