The four links look mixed together. Suggest a bullet list:

```
   * [LegCoHK](http://nbviewer.ipython.org/urls/raw.githubusercontent.com/hupili/legcohk/master/LegCoHK.ipynb)  
   * [1 PCA](http://nbviewer.ipython.org/urls/course.ie.cuhk.edu.hk/~engg4030/tutorial/tutorial7/Dimensionality-Reduction.ipynb) 
   * [2 Recommender Analysis](http://nbviewer.ipython.org/urls/course.ie.cuhk.edu.hk/~engg4030/tutorial/tutorial9/Recommender-System.ipynb) 
   * [3 Graph Analysis](http://nbviewer.ipython.org/urls/course.ie.cuhk.edu.hk/~engg4030/tutorial/tutorial10/Graph-Analysis.ipynb)
```