diff --git a/core-java-modules/core-java-concurrency-advanced-4/README.md b/core-java-modules/core-java-concurrency-advanced-4/README.md
new file mode 100644
index 0000000000..98f2894515
--- /dev/null
+++ b/core-java-modules/core-java-concurrency-advanced-4/README.md
@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Binary Semaphore vs Reentrant Lock](https://www.baeldung.com/java-binary-semaphore-vs-reentrant-lock)
diff --git a/core-java-modules/core-java-io-4/README.md b/core-java-modules/core-java-io-4/README.md
index 7cc38bb9fe..c837e2bffc 100644
--- a/core-java-modules/core-java-io-4/README.md
+++ b/core-java-modules/core-java-io-4/README.md
@@ -4,5 +4,5 @@ This module contains articles about core Java input and output (IO)
 
 ### Relevant Articles: 
 
-- [Java File Separator vs File Path Separator]
+- [Java File Separator vs File Path Separator](https://www.baeldung.com/java-file-vs-file-path-separator)
 - [[<-- Prev]](/core-java-modules/core-java-io-3)
diff --git a/guest/core-kotlin/README.md b/guest/core-kotlin/README.md
new file mode 100644
index 0000000000..c211773f27
--- /dev/null
+++ b/guest/core-kotlin/README.md
@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Kotlin vs Java](https://www.baeldung.com/kotlin/kotlin-vs-java)
diff --git a/jackson-modules/jackson-conversions-2/README.md b/jackson-modules/jackson-conversions-2/README.md
index 71c5578525..9986fe75b5 100644
--- a/jackson-modules/jackson-conversions-2/README.md
+++ b/jackson-modules/jackson-conversions-2/README.md
@@ -9,4 +9,5 @@ This module contains articles about Jackson conversions.
 - [Converting JSON to CSV in Java](https://www.baeldung.com/java-converting-json-to-csv)
 - [How to Process YAML with Jackson](https://www.baeldung.com/jackson-yaml)
 - [Jackson Streaming API](https://www.baeldung.com/jackson-streaming-api)
+- [Jackson: java.util.LinkedHashMap cannot be cast to X](https://www.baeldung.com/jackson-linkedhashmap-cannot-be-cast)
 - More articles: [[<-- prev]](../jackson-conversions)