diff --git a/src/main/java/org/jabref/gui/externalfiletype/ExternalFileType.java b/src/main/java/org/jabref/gui/externalfiletype/ExternalFileType.java
index 0a5a44259cf..fff38ae4daa 100644
--- a/src/main/java/org/jabref/gui/externalfiletype/ExternalFileType.java
+++ b/src/main/java/org/jabref/gui/externalfiletype/ExternalFileType.java
@@ -4,6 +4,9 @@
 import org.jabref.model.entry.field.Field;
 import org.jabref.model.entry.field.FieldFactory;
 
+/**
+ * "Twin" interface: {@link org.jabref.logic.util.FileType}
+ */
 public interface ExternalFileType {
     String getName();
 
diff --git a/src/main/java/org/jabref/logic/util/FileType.java b/src/main/java/org/jabref/logic/util/FileType.java
index c054d54d7bc..1d5c1f5821d 100644
--- a/src/main/java/org/jabref/logic/util/FileType.java
+++ b/src/main/java/org/jabref/logic/util/FileType.java
@@ -5,6 +5,8 @@
 
 /**
  * Interface for {@link StandardFileType} which allows us to extend the underlying enum with own filetypes for custom exporters
+ *
+ * "Twin" interface: {@link org.jabref.gui.externalfiletype.ExternalFileType}
  */
 public interface FileType {