diff --git a/docs/m04-weakties/lab04.ipynb b/docs/m04-weakties/lab04.ipynb
index 285e15d..cf44287 100644
--- a/docs/m04-weakties/lab04.ipynb
+++ b/docs/m04-weakties/lab04.ipynb
@@ -7,7 +7,7 @@
     "# Network visualization assignment\n",
     "\n",
     "<div style=\"display: flex; align-items: center;\">\n",
-    "    <a target=\"_blank\" href=\"https://colab.research.google.com/github/yy/netsci-course/blob/master/docs/m04-/lab04.ipynb\">\n",
+    "    <a target=\"_blank\" href=\"https://colab.research.google.com/github/yy/netsci-course/blob/master/docs/m04-weakties/lab04.ipynb\">\n",
     "        <img src=\"https://www.tensorflow.org/images/colab_logo_32px.png\" style=\"vertical-align: -8px; margin-right: 10px;\" />\n",
     "        Open this notebook in Google Colab\n",
     "    </a>\n",
@@ -15,7 +15,7 @@
     "\n",
     "\n",
     "<div style=\"display: flex; align-items: center;\">\n",
-    "    <a href=\"https://raw.githubusercontent.com/yy/netsci-course/master/docs/m04-/lab04.ipynb\" download>\n",
+    "    <a href=\"https://raw.githubusercontent.com/yy/netsci-course/master/docs/m04-weakties/lab04.ipynb\" download>\n",
     "        <img src=\"http://yyahn.com/netsci-course/images/download_icon.png\" style=\"vertical-align: -8px; margin-right: 10px;\" />\n",
     "        Download this notebook (File -> Save As)\n",
     "    </a>\n",