diff --git a/testing-modules/testing-libraries-2/README.md b/testing-modules/testing-libraries-2/README.md
index 7cc08a8140..d075c40919 100644
--- a/testing-modules/testing-libraries-2/README.md
+++ b/testing-modules/testing-libraries-2/README.md
@@ -4,3 +4,4 @@
 - [Guide to the System Stubs Library](https://www.baeldung.com/java-system-stubs)
 - [Code Coverage with SonarQube and JaCoCo](https://www.baeldung.com/sonarqube-jacoco-code-coverage)
 - [Exclusions from Jacoco Report](https://www.baeldung.com/jacoco-report-exclude)
+- [Gray Box Testing Using the OAT Technique](https://www.baeldung.com/java-gray-box-orthogonal-array-testing)