William M. Spears Diana F. Spears Jerry C. Hamann Rodney Heil Distributed, Physics-Based Control of Swarms of Vehicles. 137-162 2004 17 Auton. Robots 2-3 http://dx.doi.org/10.1023/B:AURO.0000033970.96785.f2 db/journals/arobots/arobots17.html#SpearsSHH04