diff --git a/core-kotlin-modules/core-kotlin-collections-2/README.md b/core-kotlin-modules/core-kotlin-collections-2/README.md
index 2dc180b5b3..64062ee704 100644
--- a/core-kotlin-modules/core-kotlin-collections-2/README.md
+++ b/core-kotlin-modules/core-kotlin-collections-2/README.md
@@ -2,6 +2,6 @@
 
 This module contains articles about core Kotlin collections.
 
-### Relevant articles:
-
+## Relevant articles:
 
+- [Aggregate Operations in Kotlin](https://www.baeldung.com/kotlin/aggregate-operations)