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index.md

@@ -54,7 +54,7 @@ Sep. 5  |                                       |              | Lab 2: Array Se
 Sep. 6  | [Linked Lists and Abstract Data Types](./lectures/Sep-6.md) | Ch. 3 sec. 1-5 |
 Sep. 8  | [Quiz 1](https://iu.instructure.com/courses/2165834/quizzes/4040693)                    |              | [Lab: work on Project 1 FloodIt!](./proj1-flood-it) | [submit](https://autograder.luddy.indiana.edu/web/project/691) |
 Sep. 11 | [More ADTs, Binary Trees](./lectures/Sep-11.md)               | Ch. 3 sec. 6-7,<br> Ch. 4 sec. 1-2 | Project 1: FloodIt! due |
-Sep. 13 | Binary Search Trees                   | Ch. 4 sec. 3 and 7  |
+Sep. 13 | [Binary Search Trees](./lectures/Sep-13)                   | Ch. 4 sec. 3 and 7  |
 Sep. 15 |  |  | [Lab 3: Merge Sort on Linked Lists](./lab3) | [test](https://autograder.luddy.indiana.edu/web/project/825), [code](https://autograder.luddy.indiana.edu/web/project/707)
 Sep. 18 |  |  |  <mark>Lab 3 due</mark> |