diff --git a/docs/Types.md b/docs/Types.md
index bfc3cb5..8ca9d05 100644
--- a/docs/Types.md
+++ b/docs/Types.md
@@ -41,7 +41,8 @@
     "volumeNumber": string,
     "chapterNumber": string,
     "url": string,
-    "fileName": string
+    "fileName": string,
+    "id": string?
 }
 ```