J. Parker, A. Khoogar, and D. Goldberg. Robotics and Automation, 1989. Proceedings., 1989 IEEE International Conference on, page 271--276. IEEE, (1989)
A. Huang, E. Olson, and D. Moore. Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Taipei, page 4057-4062. (October 2010)