added reference books

Author: elmerehbi

statinf.md

@@ -4,3 +4,8 @@ title: Statistical Inference
 permalink: /statinf/
 ---
 
+## Reference Books
+- [OpenIntro textbook](https://www.openintro.org/stat/textbook.php)
+- [Statlect - The digital textbook on probability and statistics](http://www.statlect.com/)
+- [An Introduction to Statistical Learning with Applications in R](http://www-bcf.usc.edu/~gareth/ISL/) [[PDF, 4th printing]](http://www-bcf.usc.edu/~gareth/ISL/ISLR%20Fourth%20Printing.pdf)
+- [The Elements of Statistical Learning: Data Mining, Inference, and Prediction](http://statweb.stanford.edu/~tibs/ElemStatLearn/) [[PDF, 10th ed]](http://statweb.stanford.edu/~tibs/ElemStatLearn/printings/ESLII_print10.pdf)