Workflow Control

http://www.informit.com/articles/article.aspx?p=170329&rl=1
http://www.e-workflow.org/
http://www.wfmc.org
http://www.workflowpatterns.com/evaluations/product/index.php
http://www.openflow.it/wwwopenflow/EN/Documentation/Files/WorkflowIntroduction/WfMC_Workflow_Introduction.pdf