diff --git a/.gitmodules b/.gitmodules
index 64687ac..80ce81d 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -13,3 +13,6 @@
 [submodule "book/external/Useful_python_code"]
 	path = book/external/Useful_python_code
 	url = https://github.com/TeachBooks/Useful_python_code.git
+[submodule "book/external/TeachBooks"]
+	path = book/external/TeachBooks
+	url = https://github.com/TeachBooks/TeachBooks.git
diff --git a/book/external/TeachBooks b/book/external/TeachBooks
new file mode 160000
index 0000000..cfab2f9
--- /dev/null
+++ b/book/external/TeachBooks
@@ -0,0 +1 @@
+Subproject commit cfab2f9facf8c3ddba9bcd91cfdade9541cfb361