diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9cf7af8..1588b45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,10 +35,14 @@
     define decision-making models with less flexibility than traditional
     inheritance-based models.
 
+    For more information check the tutorial [Extending Aggregation and Transformation Functions](https://scikit-criteria.quatrope.org/en/latest/tutorial/extend.html)
+
 - **New Module:** Introduced the `skcriteria.testing` module, exposing utility functions for for comparing objects created in Scikit-Criteria in a testing environment. These functions facilitate the comparison of instances of the `DecisionMatrix`, `ResultABC`, and `RanksComparator` classes.
 
   The assertion functions utilize pandas and numpy testing utilities for comparing matrices, series, and other attributes.
 
+  Check the [Reference](https://scikit-criteria.quatrope.org/en/latest/api/testing.html) for more information.
+
 - **New** The API of the agg, pipeline, preprocessing, and extend modules has
   been cleaned up to prevent autocompletion with imports from other modules.
   The imported modules are still present, but they are excluded when attempting