@misc {IOPORT.70534455,
    author       = {Zhang, Zhikun and Xiao, Jianguo and Li, Hanyi and Geng, Youping},
    title        = {An extended permission-based delegation authorization model},
    howpublished = {CSSE (3), 696-699 (2008).},
    year         = {2008},
    doi          = {10.1109/CSSE.2008.983},
    identifier   = {70534455},
}