K. Hammond, R. Burke, und S. Lytinen. Proceedings of the 14th International Joint Conference on Artificial Intelligence, Seite 2071--2072. San Francisco, CA, USA, Morgan Kaufmann Publishers Inc., (1995)
M. Zanker, und M. Jessenitschnig. Proceedings of the 2009 IEEE Conference on Commerce and Enterprise Computing, Seite 49--56. Washington, DC, USA, IEEE Computer Society, (2009)