From 6590996682681bf3b4cf40f5385c582a768381ac Mon Sep 17 00:00:00 2001
From: Sayantan Santra <35728385+SinTan1729@users.noreply.github.com>
Date: Wed, 7 Feb 2024 18:40:19 -0600
Subject: [PATCH] Update references.md

---
 references.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/references.md b/references.md
index 82adcf4..05ef13c 100644
--- a/references.md
+++ b/references.md
@@ -3,4 +3,5 @@
 1. [Mathematics in Lean by Jeremy Avigad and Patrick Massot](https://leanprover-community.github.io/mathematics_in_lean/mathematics_in_lean.pdf)
 2. [The Mathlib 4 API docs](https://leanprover-community.github.io/mathlib4_docs/)
 3. [The Lean Zulip Chat](https://leanprover.zulipchat.com/)
-
+4. [Some Lean Games](https://adam.math.hhu.de/)
+5. [The original version of The Natural Number Game](https://www.ma.imperial.ac.uk/~buzzard/xena/natural_number_game/index2.html)