8ARMACOST A P, BARNHART C, WARE K A. Composite variable formulations for express shipment service network design [ J ]. Transportation Science, 2002,36( 1 ) : 1 - 20.
9ARMACOST A P, BARNHART C, WARE K A, et al. UPS optimizes its air network[ J]. Interfaces,2004, 34(1) :15 -25.
10NGAMCHAI S. Air express network design with hub sorting[ D]. Washington: University of Maryland,2007.