C. Lynch, K. Ashley, V. Aleven, and N. Pinkwart. Proc. ITS 2006 Workshop on Intelligent Tutoring Systems for Ill-Defined
Domains, volume 4053 of LNCS, page 1--10. Jhongli, Taiwan, Springer, (2006)
R. Nance, and J. Arthur. SW'06: Proc. 3rd Operational Research Society Simulation Workshop, page 117--127. Birmingham, UK, The Operational Research Society, (2006)