diff --git a/README.md b/README.md
index ba97df6..5973b03 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 # webprofile-ref-project
-Reference implementation for the book, "A guide to OpenSAML" 
+Reference implementation for the book, "A guide to OpenSAML V3" 
+
+The book is availible here: https://gumroad.com/l/a-guide-to-opensaml-v3
 
 The sole purpose of the sample project is to illustrate the function of OpenSAML. 
-Although, it can be a very good place to start when experimenting with OpenSAML, it should not be used for production purposes.
+Although, it can be a very good place to start when experimenting with OpenSAML, it should not be used for production purposes.
\ No newline at end of file