diff --git a/book/_toc.yml b/book/_toc.yml
index 41c8f76..4c5006b 100644
--- a/book/_toc.yml
+++ b/book/_toc.yml
@@ -11,6 +11,7 @@ parts:
       sections:
       - file: exercises/001.md
       - file: exercises/002.md
+      - file: exercises/003.md
     - file: references.md
     - file: changelog.md
     - file: credits.md