1. On the complexity of motion planning for multiple independent objects; PSPACE-hardness of the “Warehouseman’s problem”;Hopcroft;International Journal of Robotics Research,1984
2. D. Ratner, M. Warmuth, Finding a shortest solution for the NN extension of the 15-puzzle is intractable, in: Proceedings of AAAI National Conference on Artificial Intelligence, AAAI-86, 1986, pp. 168–172.
3. P. Surynek, An optimization variant of multi-robot path planning is intractable, in: Proceedings of the 24th AAAI Conference on Artificial Intelligence, AAAI-10, 2010, pp. 1261–1263.
4. Dynamic game applied to coordination control of two arm robotic system;Ardema,1991
5. D. Parsonsand, J. Canny, A motion planner for multiple mobile robots, in: IEEE Int. Conf. on Robotics and Automation, 1990, pp. 8–13.