Zhijiao Xiao HuiYou Chang Sijia Wen Yang Yi Atsushi Inoue An Extended Meta-model for Workflow Resource Model. 525-534 2006 conf/ksem/2006 KSEM http://dx.doi.org/10.1007/11811220_44 db/conf/ksem/ksem2006.html#XiaoCWYI06