diff --git a/README.md b/README.md
index ace8905..0455b0e 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,7 @@ For each notebook you can hover on the title to see a description, or click the
 
 |Open|Year|New|
 |---|---|---|
+| [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/lispy.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/lispy.ipynb) | 2026 | <a href="ipynb/lispy.ipynb" title="Tutorial on interpreters.">(How to Write a (Lisp) Interpreter (in Python))</a> |
 | [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/RationalPi.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/RationalPi.ipynb) | 2026 | <a href="ipynb/RationalPi.ipynb" title="Using continued fractions to find fractions (like 22/7) that are close to pi.">Approximating Pi with a Fraction</a> |
 | [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/clvr.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/clvr.ipynb) | 2026 | <a href="ipynb/clvr.ipynb" title="Guess famous phrases from letter shapes. Beginner level.">Did you solve it? R y clvr ngh t rd ths sntnc?</a> |
 | [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/Euler3.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/Euler3.ipynb) | 2026 | <a href="ipynb/Euler3.ipynb" title="Find the largest prime factor of a number">Project Euler #3: Largest prime factor</a> |
@@ -150,6 +151,7 @@ For each notebook you can hover on the title to see a description, or click the
 |---|---|---|
 | [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/BASIC.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/BASIC.ipynb) | 2017 | <a href="ipynb/BASIC.ipynb" title="How to write an interpreter for the BASIC programming language">BASIC Interpreter</a> |
 | [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/Convex%20Hull.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/Convex%20Hull.ipynb) | 2017 | <a href="ipynb/Convex%20Hull.ipynb" title="A classic Computer Science Algorithm">Convex Hull Problem</a> |
+| [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/lispy.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/lispy.ipynb) | 2026 | <a href="ipynb/lispy.ipynb" title="Tutorial on interpreters.">(How to Write a (Lisp) Interpreter (in Python))</a> |
 | [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/DocstringFixpoint.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/DocstringFixpoint.ipynb) | 2023 | <a href="ipynb/DocstringFixpoint.ipynb" title="An approach to writing code and docstrings that go together.">Docstring Fixpoint Theory</a> |
 | [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/StableMatching.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/StableMatching.ipynb) | 2020 | <a href="ipynb/StableMatching.ipynb" title="What is the best way to pair up two groups with each other, obeying preferences?">Stable Matching Problem</a> |
 | [co](https://colab.research.google.com/github/norvig/pytudes/blob/main/ipynb/Differentiation.ipynb) [nb](https://nbviewer.jupyter.org/github/norvig/pytudes/blob/main/ipynb/Differentiation.ipynb) | 2017 | <a href="ipynb/Differentiation.ipynb" title="A computer algebra system, including symbolic differentiation">Symbolic Algebra, Simplification, and Differentiation</a> |