diff --git a/units/en/unit1/exp-exp-tradeoff.mdx b/units/en/unit1/exp-exp-tradeoff.mdx
index 10798d8..451adde 100644
--- a/units/en/unit1/exp-exp-tradeoff.mdx
+++ b/units/en/unit1/exp-exp-tradeoff.mdx
@@ -26,7 +26,7 @@ If it’s still confusing, **think of a real problem: the choice of picking a re
 
 <figure>
 <img src="https://huggingface.co/datasets/huggingface-deep-rl-course/course-images/resolve/main/en/unit1/exp_2.jpg" alt="Exploration">
-<figcaption>Source: <a href="[http://rail.eecs.berkeley.edu/deeprlcourse-fa17/f17docs/lecture_13_exploration.pdf](http://rail.eecs.berkeley.edu/deeprlcourse-fa17/f17docs/lecture_13_exploration.pdf)"> Berkley AI Course</a>
+<figcaption>Source: <a href="https://inst.eecs.berkeley.edu/~cs188/sp20/assets/lecture/lec15_6up.pdf"> Berkley AI Course</a>
 </figcaption>
 </figure>