diff --git a/.github/workflows/run-notebooks.yml b/.github/workflows/run-notebooks.yml
index 8ccba27..22a68ed 100644
--- a/.github/workflows/run-notebooks.yml
+++ b/.github/workflows/run-notebooks.yml
@@ -56,14 +56,23 @@ jobs:
       - name: Setup Graphviz
         uses: ts-graphviz/setup-graphviz@v1
 
+      - name: Install Linux packages
+        if: matrix.os == 'ubuntu-latest'
+        run: |
+          sudo apt-get install libcairo2-dev
+          sudo apt-get clean
+
       - name: Install dependencies
         run: |
+          df -h
+          mkdir cache
           conda install scipy
           conda install conda-forge::fdasrsf
+          conda install conda-forge::cairo
           pip install --upgrade pip
           pip install --upgrade wheel
           pip install --upgrade jinja2
-          pip install -r requirements-modern.txt
+          pip install --no-cache-dir -r requirements-modern.txt
           cat requirements-modern.txt
 
       - name: Execute notebooks
@@ -113,7 +122,7 @@ jobs:
         if: matrix.os == 'ubuntu-latest'
         run: |
           sudo apt install -y graphviz
-          sudo apt-get install libblas-dev liblapack-dev
+          sudo apt-get install libblas-dev liblapack-dev libcairo2-dev
 
       - name: Install dependencies
         run: |
diff --git a/IndustrialStatistics/notebooks/Chap004.ipynb b/IndustrialStatistics/notebooks/Chap004.ipynb
index 1edba92..4a92fe6 100644
--- a/IndustrialStatistics/notebooks/Chap004.ipynb
+++ b/IndustrialStatistics/notebooks/Chap004.ipynb
@@ -404,7 +404,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 30,
+   "execution_count": null,
    "id": "645130df",
    "metadata": {
     "colab": {
@@ -438,7 +438,7 @@
     "diss = mistat.load_data('DISS')\n",
     "columns = ['batch', 'min15', 'min90']\n",
     "\n",
-    "mahalanobisT2 = MahalanobisT2(diss[columns], 'batch',\n",
+    "mahalanobisT2 = mistat.MahalanobisT2(diss[columns], 'batch',\n",
     "    compare_to=[15,15], conf_level=0.95)\n",
     "mahalanobisT2.summary()"
    ]