http://baike.baidu.com/link?url=eNLcTr8tA-EQqp3B8NltPjFhVMwWZO-pF4Ax1u3kP9NvhjdYq567ZC_BHfIj8M5dAA0V78b_YPFZCfatdeD7bK
http://vdisk.weibo.com/s/q8gG6oVWZULA
http://wenku.baidu.com/link?url=Sv5CSHh3NcedRjvR5IfGesFzoU7SzJ4JCzSRH1Mfv_JzTn2yYNlY21rqaKsEU1gi-goZbDUgzVjS-rIvfpgncFg5AB6_4BozThDjrdP_x6O
逼近理论
原文:http://www.cnblogs.com/Wanggcong/p/5111565.html