diff --git a/README.md b/README.md
index d58706ff..b6814b9b 100644
--- a/README.md
+++ b/README.md
@@ -532,14 +532,12 @@ Should you want to use very specific/advanced features of some of the formats, y
 
 q: How does it work?
 
-a: The TwelveMonkeys ImageIO project contains plug-ins for ImageIO.
-
-ImageIO uses a service lookup mechanism, to discover plug-ins at runtime.
-
-TODO: Describe SPI mechanism.
+a: The TwelveMonkeys ImageIO project contains plug-ins for ImageIO. ImageIO uses a service lookup mechanism, to discover plug-ins at runtime. 
 
 All you have have to do, is to make sure you have the TwelveMonkeys JARs in your classpath.
 
+You can read more about the registry and the lookup mechanism in the [IIORegistry API doc](http://docs.oracle.com/javase/7/docs/api/javax/imageio/spi/IIORegistry.html).
+
 The fine print: The TwelveMonkeys service providers for TIFF and JPEG overrides the onRegistration method, and
 utilizes the pairwise partial ordering mechanism of the IIOServiceRegistry to make sure it is installed before
 the Sun/Oracle provided JPEGImageReader and the Apple provided TIFFImageReader on OS X, respectively.