diff --git a/ipynb/CrossProduct.ipynb b/ipynb/CrossProduct.ipynb
index 12517fa..2925c9f 100644
--- a/ipynb/CrossProduct.ipynb
+++ b/ipynb/CrossProduct.ipynb
@@ -4,7 +4,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "<div align=\"right\" style=\"text-align: right\"><i>Peter Norvig, Feb 2020</i></div>\n",
+    "<div align=\"right\" style=\"text-align: right\"><i>Peter Norvig, Feb 2021</i></div>\n",
     "\n",
     "# CrossProduct Puzzle\n",
     "\n",