diff --git a/SMOS_ESSD_Ant.ipynb b/SMOS_ESSD_Ant.ipynb
index d37a2afd08422bac21da0f5f8fc366baaeea4cf3..f7edfe7d7cca4fb5ed9dce11bfc8bca03620cc45 100755
--- a/SMOS_ESSD_Ant.ipynb
+++ b/SMOS_ESSD_Ant.ipynb
@@ -24,7 +24,21 @@
     "\n",
     " * Helicopter-based EM Bird (HEM) data¶\n",
     " * Surface and Under-Ice Trawl (SUIT)\n",
-    " * Upward-Looking Sonars (ULS)\n"
+    " * Upward-Looking Sonars (ULS)\n",
+    " \n",
+    "The data sources are given below.\n",
+    "\n",
+    "## Module versions\n",
+    "\n",
+    "The code runs with the following versions:\n",
+    "\n",
+    "    python                    3.9.9           h62f1059_0_cpython    conda-forge\n",
+    "    xarray                    0.19.0             pyhd8ed1ab_0    conda-forge\n",
+    "    matplotlib                3.4.2            py39hf3d152e_0    conda-forge\n",
+    "    basemap                   1.2.2            py39h2103e0b_3    conda-forge\n",
+    "    pandas                    1.3.1            py39hde0f152_0    conda-forge\n",
+    "    pyproj                    3.2.1            py39ha9a7ae0_2    conda-forge\n",
+    "    "
    ]
   },
   {
@@ -229,7 +243,7 @@
     "\n",
     "Behrendt, A., Dierking, W., Fahrbach, E., and Witte, H.: Sea ice draft in the Weddell Sea, measured by upward looking sonars, Earth Syst. Sci. Data, 5, 209–226, https://doi.org/10.5194/essd-5-209-2013, 2013.\n",
     "\n",
-    "Behrendt, A., W. Dierking, and H. Witte(2015), Thermodynamic sea ice growthin the central Weddell Sea, observed inupward-looking sonar data,J. Geophys.Res. Oceans,120, 2270–2286,doi:10.1002/2014JC010408\n",
+    "Behrendt, A., W. Dierking, and H. Witte (2015), Thermodynamic sea ice growth in the central Weddell Sea, observed in upward-looking sonar data, J. Geophys. Res. Oceans,120, 2270–2286,doi:10.1002/2014JC010408\n",
     "\n",
     "The sea ice thickness in the Atlantic sector of the Southern Ocean, PhD thesis Axel Behrendt, 2013\n",
     "http://wwwdb.dbod.de/login?url=https://d-nb.info/1072077566/34\n",
@@ -274,9 +288,9 @@
    ],
    "source": [
     "# Download data from Pangaea https://doi.org/10.5194/essd-5-209-2013 \n",
-    "# and store in the directory ULS_dir\n",
+    "# and store in the directory ULS_dir.\n",
     "# Download ZIP file containing all datasets as tab-delimited text\n",
-    "\n",
+    "# unzip Behrendt_2013.zip\n",
     "ULS_dir=\"repo_data/ULS_Ant_Behrendt_2013/\"\n",
     "!ls $ULS_dir"
    ]