1. LIU Z X, WANG S. The computer simulation study of port tugboat operation [J]. Journal of System Simulation, 2004, 16(1): 45–47 (in Chinese).
2. LIU Z X. Hybrid evolutionary strategy optimization for port tugboat operation scheduling [C] //2009 Third International Symposium on Intelligent Information Technology Application. Nanchang: IEEE, 2009: 511–515.
3. DONG L C, XU Z Q, MI W J. The dynamic tugboat schedule based on particle swarm algorithm combined with genetic operators [J]. Mathematics in Practice and Theory, 2012, 42(6): 122–133 (in Chinese).
4. WANG W, ZHAO H, LI Q. Multi-objectives optimization for port tugboat scheduling considering multi-anchorage bases [J]. Computer Engineering and Applications, 2013, 49(13): 8–12 (in Chinese).
5. WANG S, ZHU M, KAKU I, et al. An improved discrete PSO for tugboat assignment problem under a hybrid scheduling rule in container terminal [J]. Mathematical Problems in Engineering, 2014, 2014: 1–10.