1. Barry & Associates. (2002). Web service explained. http://www.service-architecture.com/web-services/articles/web_services_explained.html .
2. Einspanier, U., Lutz, M., Senkler, M., Simonis, I., & Sliwinski, A. (2003). Toward a process model for GI service composition. KSL Stanford. http://www.delphi-imm.de/meanings/documents/Einspanier_et_al_Toward_Process_Model_for_GI_Service_Composition.pdf .
3. Heckel, R. (2003). Open Petri nets as semantic model for workflow integration. In Lecture Notes in Computer Science (Vol. 2472(5), pp. 281–294). Berlin: Springer.
4. Kawamura, P. M. (2002). Towards a semantic choreography of web services: From WSDL to DAML-S. In CAiSE Conference (pp. 225–236).
5. Kumar A. (2002) Workflow support for electronic commerce applications. Decision Support Systems 32(3): 265–278