diff --git a/README.md b/README.md
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+++ b/README.md
@@ -28,6 +28,7 @@ $ pip install -e .
 
 # Day 3 Resources
 - *Python Typing is for Humans*: [Unital.dev blog](https://www.unital.dev/blog/python-typing-is-for-humans/) or [LinkedIn](https://www.linkedin.com/pulse/python-typing-humans-corran-webster-u66ee)
+- [*Domain Driven Design*](https://www.oreilly.com/library/view/domain-driven-design-tackling/0321125215/) (O'Reilly)
 - [PyData Sphinx Theme](https://pydata-sphinx-theme.readthedocs.io/en/stable/)
 - [Sphinx AutoAPI](https://sphinx-autoapi.readthedocs.io/en/latest/)
 - Find the refactoring Give It A Try in `files/convert_mass.py`