http://www.paper.edu.cn/files/resultshare/chenenhong/A.pdf
http://cjis.sem.tsinghua.edu.cn/Journals/Journal-2-2/8.pdf
http://www.paper.edu.cn/files/resultshare/chenenhong/A.pdf
http://cjis.sem.tsinghua.edu.cn/Journals/Journal-2-2/8.pdf