diff --git a/core-java-modules/core-java-string-operations-4/README.md b/core-java-modules/core-java-string-operations-4/README.md
index be4c9ae05f..83bfeb4d05 100644
--- a/core-java-modules/core-java-string-operations-4/README.md
+++ b/core-java-modules/core-java-string-operations-4/README.md
@@ -2,4 +2,5 @@
 
 - [Ignoring Commas in Quotes When Splitting a Comma-separated String](https://www.baeldung.com/java-split-string-commas)
 - [Compare Strings While Ignoring Whitespace in Java](https://www.baeldung.com/java-compare-string-whitespace)
+- [Concatenating Null Strings in Java](https://www.baeldung.com/java-concat-null-string)