Update README.md

Author: Cheng-Lin-Li

README.md

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 # Machine Learning
 Implementations of machine learning algorithm by Python 3
 
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 ## Reference:
+* Machine Learning at Coursera: https://www.coursera.org/learn/machine-learning/
 * Machine Learning Course CS229 at Stanford: https://see.stanford.edu/Course/CS229
 * Machine Learning Foundations at NTU: https://www.youtube.com/watch?v=nQvpFSMPhr0&list=PLXVfgk9fNX2I7tB6oIINGBmW50rrmFTqf
 * Machine Learning Techniques at NTU: https://www.youtube.com/watch?v=A-GxGCCAIrg&list=PLXVfgk9fNX2IQOYPmqjqWsNUFl2
 * Hidden Markov model (HMM): https://en.wikipedia.org/wiki/Hidden_Markov_model
 * Viterbi Algorithm: http://homepages.ulb.ac.be/~dgonze/TEACHING/viterbi.pdf
 * LSTM: http://colah.github.io/posts/2015-08-Understanding-LSTMs/
+* PCA at wikipedia: https://en.wikipedia.org/wiki/Principal_component_analysis
+
 
 Cheng-Lin Li@University of Southern California
-[email protected] or 
-[email protected]
+emailto: [email protected] or [email protected]