Fix the "Clean Code" book link

README.md

@@ -233,7 +233,7 @@ Please see [CONTRIBUTING](CONTRIBUTING.md) for details and contribute. ;)
 * [Agile Principles, Patterns, and Practices in C#](http://books.google.com/books/about/Agile_Principles_Patterns_and_Practices.html?id=x4tQAAAAMAAJ&redir_esc=y)
 * [Growing Object-Oriented Software, Guided by Tests](http://books.google.com/books/about/Growing_Object_Oriented_Software_Guided.html?id=fOyYCR4oYs0C&redir_esc=y)
 * [Test Driven Development: By Example](http://books.google.com/books/about/Test_driven_Development.html?id=gFgnde_vwMAC&redir_esc=y)
-* [Clean Code: A Handbook of Agile Software Craftsmanship](books.google.com/books/about/Clean_Code.html?id=_i6bDeoCQzsC&redir_esc=y)
+* [Clean Code: A Handbook of Agile Software Craftsmanship](http://books.google.com/books/about/Clean_Code.html?id=_i6bDeoCQzsC&redir_esc=y)
 * [Refactoring: Improving the Design of Existing Code](http://books.google.com/books/about/Refactoring.html?id=1MsETFPD3I0C&redir_esc=y)
 * [UML Distilled: A Brief Guide to the Standard Object Modeling Language](http://books.google.com/books/about/UML_Distilled.html?id=nHZslSr1gJAC&redir_esc=y)
 * [Patterns of Enterprise Application Architecture](http://books.google.com/books/about/Patterns_of_Enterprise_Application_Archi.html?id=FyWZt5DdvFkC&redir_esc=y)