1. J.T. Betts, http://www.boeing.com/phantom/socs/index.html
2. A.L. Schwartz, E. Polak, Y.Q. Chen, http://www.accesscom.com/~adam/RIOTS/
3. O. von Stryk, http://www.sim.informatik.tu-darmstadt.de/sw/dircol.html.en
4. L.S. Jennings, M.E. Fisher, K.L.Teo, C.J. Goh, http://www.cado.uwa.edu.au/miser/
5. C.A. Schweiger, Ch.A. Floudas, http://titan.princeton.edu/MINOPT/minopt.html