https://www.amazon.com/Speech-Language-Processing-Daniel-Jurafsky/dp/0131873210
http://web.stanford.edu/~jurafsky/slp3/
http://www.nltk.org/book/
https://www.amazon.com/Natural-Language-Processing-Python-Analyzing/dp/0596516495/ref=pd_sim_14_2?_encoding=UTF8&pd_rd_i=0596516495&pd_rd_r=A2G2WV4H37HZXQM4J4ZR&pd_rd_w=cooCl&pd_rd_wg=2OT81&psc=1&refRID=A2G2WV4H37HZXQM4J4ZR&dpID=51ezTmJ6XFL&preST=_SX218_BO1,204,203,200_QL40_&dpSrc=detail