Update references.md

Author: sravanthimodepu

experiment/references.md

@@ -1,9 +1,7 @@
 1. Image Arithmetic - [http://homepages.inf.ed.ac.uk/rbf/HIPR2/arthops.htm](http://homepages.inf.ed.ac.uk/rbf/HIPR2/arthops.htm)
 
-2. Image Arithmetic - [http://www.student.kuleuven.be/~m0216922/CG/imagearithmetic.html](http://www.student.kuleuven.be/~m0216922/CG/imagearithmetic.html)
-
-Books:
+**Books:**
 
 1. A.K.Jain, Fundamentals of Digital Image Processing, Prentice-Hall, 1989.
 
-2. Rafael C. Gonzalez, Digital Image Processing, Second Ed., Pearson Education,2004. 
+2. Rafael C. Gonzalez, Digital Image Processing, Second Ed., Pearson Education,2004.