http://www.open-open.com/doc/view/7e983c0bf1594849bcd088dc212098c4

http://wenku.baidu.com/link?url=crsPiPMrjNC9v7-ikKMIPNpQ1Pkb7noEPo8q1vPCm3eyOw0TWQ8NaeUSfd42dwgU-LFWb_rbH4tNVFWUe6D2PJGmSY3GB7LK_kWzNwJvHYm

http://www.52nlp.cn/%E4%B8%AD%E6%96%87%E5%88%86%E8%AF%8D%E5%85%A5%E9%97%A8%E4%B9%8B%E5%AD%97%E6%A0%87%E6%B3%A8%E6%B3%954

http://www.doc88.com/p-0983762368170.html

http://www.nltk.org/api/nltk.tag.html

http://www.docin.com/p-226011470.html

https://pypi.python.org/pypi/python-crfsuite

http://www.52nlp.cn/%E6%9D%A1%E4%BB%B6%E9%9A%8F%E6%9C%BA%E5%9C%BA%E6%96%87%E7%8C%AE%E9%98%85%E8%AF%BB%E6%8C%87%E5%8D%97

http://www.inference.phy.cam.ac.uk/hmw26/crf/

http://blog.csdn.net/happyzhouxiaopei/article/details/7960876