diff --git a/doc/groups.dox b/doc/groups.dox
--- a/doc/groups.dox
+++ b/doc/groups.dox
@@ -464,7 +464,7 @@
 */
 
 /**
-@defgroup lemon_io LEMON Input-Output
+@defgroup lemon_io LEMON Graph Format
 @ingroup io_group
 \brief Reading and writing LEMON Graph Format.
 
@@ -482,6 +482,13 @@
 */
 
 /**
+@defgroup nauty_group NAUTY Format
+@ingroup io_group
+\brief Read \e Nauty format
+Tool to read graphs from \e Nauty format data.
+*/
+
+/**
 @defgroup concept Concepts
 \brief Skeleton classes and concept checking classes