diff --git a/src/teaching/cse-250/2022fa/slide/10b-Recursion.erb b/src/teaching/cse-250/2022fa/slide/10b-Recursion.erb
index f87508de..1984b07f 100644
--- a/src/teaching/cse-250/2022fa/slide/10b-Recursion.erb
+++ b/src/teaching/cse-250/2022fa/slide/10b-Recursion.erb
@@ -2,7 +2,7 @@
 template: templates/cse250_2022_slides.erb
 title: Recursion
 date: Sept 21, 2022
-textbook: tbd
+textbook: Ch. 15
 ---
 
 <section>