Boualem Benatallah Piotr Chrzastowski-Wachtel Rachid Hamadi Milton O'Dell Adi Susanto HiWorD: A Petri Net-Based Hierarchical Workflow Designer. 235-236 2003 conf/acsd/2003 ACSD http://csdl.computer.org/comp/proceedings/acsd/2003/1887/00/18870235.pdf db/conf/acsd/acsd2003.html#BenatallahCHOS03