1. Aarts, E., Lenstra, J.K.: Local Search in Combinatorial Optimization. John Wiley & Sons, Inc., Chichester (1997)
2. Lecture Notes in Computer Science;K.R. Apt,1997
3. Apt, K.R.: Principles of Constraint Programming. Cambridge University Press, Cambridge (2003)
4. Lecture Notes in Computer Science;N. Barnier,1998
5. Burke, E.K., Elliman, D., Weare, R.F.: A hybrid genetic algorithm for highly constrained timetabling problems. In: Proc. of ICGA, pp. 605–610. Morgan Kaufmann, San Francisco (1995)