diff --git a/core-java-concurrency/README.md b/core-java-concurrency/README.md
index 682c9b8ef0..2db7b91cde 100644
--- a/core-java-concurrency/README.md
+++ b/core-java-concurrency/README.md
@@ -26,7 +26,6 @@
 - [ExecutorService - Waiting for Threads to Finish](http://www.baeldung.com/java-executor-wait-for-threads)
 - [wait and notify() Methods in Java](http://www.baeldung.com/java-wait-notify)
 - [Priority-based Job Scheduling in Java](http://www.baeldung.com/java-priority-job-schedule)
-- [A Custom Spring SecurityConfigurer](http://www.baeldung.com/spring-security-custom-configurer)
 - [Life Cycle of a Thread in Java](http://www.baeldung.com/java-thread-lifecycle)
 - [Runnable vs. Callable in Java](http://www.baeldung.com/java-runnable-callable)
 - [Brief Introduction to Java Thread.yield()](https://www.baeldung.com/java-thread-yield)