//-->
Transportation costs and the social savings of railroads in Latin America
Zegarra B, Luis Felipe, (2013)
Economies of scale in the US airline industry
Johnston, Ahren, (2013)
Speed-flow relations and cost functions for congested traffic : theory and empirical analysis
Verhoef, Erik T., (2003)
Airline efficiency
Bitzan, John D., (2016)
Industry costs and consolidation : efficiency gains and mergers in the US railroad industry
Bitzan, John D., (2007)
Airline Efficiency