diff --git a/book b/book
index 66f5a73..4bbdd3e 160000
--- a/book
+++ b/book
@@ -1 +1 @@
-Subproject commit 66f5a732e7850764913415a6d15a24e5f3a8ba13
+Subproject commit 4bbdd3edfb0d5c23bd50ec2c032401fe711ebe20