Chia-Hung Chen and  Shangyao Yan,  Applying Lagrangian Relaxation-Based Algorithm for the Airline Coordinated Flight Scheduling Problems.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    June 2010, vol. 42(6). 660 - 667
    [viewed 25 April 2024]. Available from: https://publications.waset.org/pdf/10886.