Dongyang Long Weijia Jia Ming Li 727-742 2003 80 Int. J. Comput. Math. 6 http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=0020-7160&volume=80&issue=6&spage=727 db/journals/ijcm/ijcm80.html#LongJL03