try the following links

來源: 於 2009-04-20 11:44:09 [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次

http://www.mathlinks.ro/Forum/resources.php?c=1&cid=16
http://www.mathlinks.ro/Forum/resources.php?sid=adc7d5187b16032883b00c51085d307e