diff --git a/book/external/mechanics-BSc b/book/external/mechanics-BSc
index 261540a..9ee18fe 160000
--- a/book/external/mechanics-BSc
+++ b/book/external/mechanics-BSc
@@ -1 +1 @@
-Subproject commit 261540a7f0682495d55f8eaefe908f741286826d
+Subproject commit 9ee18fe36687e07d1c9a73d3378d225124ab3d2a