diff --git a/books/free-programming-books-langs.md b/books/free-programming-books-langs.md
index 2f18c1b93..67e04a0c0 100644
--- a/books/free-programming-books-langs.md
+++ b/books/free-programming-books-langs.md
@@ -2094,8 +2094,9 @@ Books on general-purpose programming that don't focus on a specific language are
 * [The Recursive Book of Recursion](https://inventwithpython.com/recursion/) - Al Sweigart (HTML) (3.x)
 * [The Standard Python Library](https://web.archive.org/web/20200626001242/http://effbot.org/librarybook/) - Fredrik Lundh *( :card_file_box: archived)*
 * [Think Complexity](https://greenteapress.com/wp/think-complexity-2e/) - Allen B. Downey (2nd Edition) (PDF, HTML)
-* [Think DSP - Digital Signal Processing in Python](https://greenteapress.com/wp/think-dsp/) - Allen B. Downey (PDF, HTML) (CC BY-NC)
-* [Think Python 2nd Edition](https://greenteapress.com/wp/think-python-2e/) - Allen B. Downey (3.x) (HTML, PDF) (CC BY-NC)
+* [Think DSP - Digital Signal Processing in Python](https://greenteapress.com/wp/think-dsp/) - Allen B. Downey (PDF, HTML)
+* [Think Python 3rd Edition](https://greenteapress.com/wp/think-python-3rd-edition/) - Allen B. Downey (3.x) (HTML, PDF) (CC BY-NC)
+    * [Think Python 2nd Edition](https://greenteapress.com/wp/think-python-2e/) - Allen B. Downey (3.x) (HTML, PDF) (CC BY-NC)
     * [Think Python First Edition](https://greenteapress.com/wp/think-python/) - Allen B. Downey (2.x) (HTML, PDF) (CC BY-NC)
 * [Tiny Python 3.6 Notebook](https://github.com/mattharrison/Tiny-Python-3.6-Notebook) - Matt Harrison (3.6)
 * [Tiny Python Projects](http://tinypythonprojects.com/Tiny_Python_Projects.pdf) - Ken Youens-Clark(PDF)