diff --git a/notebooks/sky130_gm.ipynb b/notebooks/sky130_gm.ipynb
index 15c720b..646bbdd 100644
--- a/notebooks/sky130_gm.ipynb
+++ b/notebooks/sky130_gm.ipynb
@@ -42,7 +42,8 @@
         "\n",
         "Boris Murmann, August 2022<br>\n",
         "Based on:\n",
-        "[sky130-raw-data-viz.ipynb](https://colab.research.google.com/github/proppy/skywater-pdk-sky130-raw-data/blob/notebooks/notebooks/sky130-raw-data-viz.ipynb)\n"
+        "[sky130-raw-data-viz.ipynb](https://colab.research.google.com/github/proppy/skywater-pdk-sky130-raw-data/blob/notebooks/notebooks/sky130-raw-data-viz.ipynb)<br>\n",
+        "SPDX-License-Identifier: Apache-2.0\n"
       ],
       "metadata": {
         "id": "zfiP46zb1v0E"