diff --git a/book/external/TeachBooks b/book/external/TeachBooks
index cfab2f9..e813313 160000
--- a/book/external/TeachBooks
+++ b/book/external/TeachBooks
@@ -1 +1 @@
-Subproject commit cfab2f9facf8c3ddba9bcd91cfdade9541cfb361
+Subproject commit e813313e8d896c77847b5af7a0a8a5f1f8bfaddc