#55 Added book reference

Author: iluwatar

README.md

@@ -776,6 +776,7 @@ Java-design-patterns project uses [semantic versioning](http://semver.org/) sche
 * [Flux - Application architecture for building user interfaces](http://facebook.github.io/flux/)
 * [Richard Pawson - Naked Objects](http://downloads.nakedobjects.net/resources/Pawson%20thesis.pdf)
 * [Patterns of Enterprise Application Architecture](http://www.amazon.com/Patterns-Enterprise-Application-Architecture-Martin/dp/0321127420)
+* [Spring Data](http://www.amazon.com/Spring-Data-Mark-Pollack/dp/1449323952/ref=sr_1_1)