diff --git a/core/modules/entity_reference/src/Annotation/EntityReferenceSelection.php b/core/modules/entity_reference/src/Annotation/EntityReferenceSelection.php
index afc6036..5779341 100644
--- a/core/modules/entity_reference/src/Annotation/EntityReferenceSelection.php
+++ b/core/modules/entity_reference/src/Annotation/EntityReferenceSelection.php
@@ -12,6 +12,15 @@
 /**
  * Defines a EntityReferenceSelection annotation object.
  *
+ * Plugin Namespace: Plugin\entity_reference\selection
+ *
+ * For a working example, see \Drupal\comment\Plugin\entity_reference\selection\CommentSelection
+ *
+ * @see \Drupal\entity_reference\Plugin\Type\SelectionPluginManager
+ * @see \Drupal\entity_reference\Plugin\Type\Selection\SelectionInterface
+ * @see \Drupal\entity_reference\Plugin\entity_reference\selection\SelectionBase
+ * @see plugin_api
+ *
  * @Annotation
  */
 class EntityReferenceSelection extends Plugin {
diff --git a/core/modules/entity_reference/src/Plugin/Type/Selection/SelectionInterface.php b/core/modules/entity_reference/src/Plugin/Type/Selection/SelectionInterface.php
index 27e1f21..e9b0ce9 100644
--- a/core/modules/entity_reference/src/Plugin/Type/Selection/SelectionInterface.php
+++ b/core/modules/entity_reference/src/Plugin/Type/Selection/SelectionInterface.php
@@ -16,7 +16,11 @@
  * This interface details the methods that most plugin implementations will want
  * to override. See \Drupal\field\Plugin\Type\Selection\SelectionBaseInterface
  * for base wrapping methods that should most likely be inherited directly from
- * Drupal\entity_reference\Plugin\Type\Selection\SelectionBase.
+ *
+ * @see \Drupal\entity_reference\Plugin\Type\SelectionPluginManager
+ * @see \Drupal\entity_reference\Annotation\EntityReferenceSelection
+ * @see \Drupal\entity_reference\Plugin\entity_reference\selection\SelectionBase
+ * @see plugin_api
  */
 interface SelectionInterface {
 
diff --git a/core/modules/entity_reference/src/Plugin/Type/SelectionPluginManager.php b/core/modules/entity_reference/src/Plugin/Type/SelectionPluginManager.php
index aa44f1c..e4fe62c 100644
--- a/core/modules/entity_reference/src/Plugin/Type/SelectionPluginManager.php
+++ b/core/modules/entity_reference/src/Plugin/Type/SelectionPluginManager.php
@@ -19,6 +19,11 @@
 
 /**
  * Plugin type manager for the Entity Reference Selection plugin.
+ *
+ * @see \Drupal\entity_reference\Annotation\EntityReferenceSelection
+ * @see \Drupal\entity_reference\Plugin\Type\Selection\SelectionInterface
+ * @see \Drupal\entity_reference\Plugin\entity_reference\selection\SelectionBase
+ * @see plugin_api
  */
 class SelectionPluginManager extends DefaultPluginManager {
 
diff --git a/core/modules/entity_reference/src/Plugin/entity_reference/selection/SelectionBase.php b/core/modules/entity_reference/src/Plugin/entity_reference/selection/SelectionBase.php
index ae4f5fc..90efbdb 100644
--- a/core/modules/entity_reference/src/Plugin/entity_reference/selection/SelectionBase.php
+++ b/core/modules/entity_reference/src/Plugin/entity_reference/selection/SelectionBase.php
@@ -24,6 +24,11 @@
  *   weight = 0,
  *   derivative = "Drupal\entity_reference\Plugin\Derivative\SelectionBase"
  * )
+ *
+ * @see \Drupal\entity_reference\Plugin\Type\SelectionPluginManager
+ * @see \Drupal\entity_reference\Annotation\EntityReferenceSelection
+ * @see \Drupal\entity_reference\Plugin\Type\Selection\SelectionInterface
+ * @see plugin_api
  */
 class SelectionBase implements SelectionInterface {