diff --git a/frontend/textbooks/physics_9_ch1.html b/frontend/textbooks/physics_9_ch1.html
index 0322e61..b15ffb9 100644
--- a/frontend/textbooks/physics_9_ch1.html
+++ b/frontend/textbooks/physics_9_ch1.html
@@ -14,11 +14,11 @@
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