diff --git a/Localization/extended_kalman_filter/extended_kalman_filter_localization.ipynb b/Localization/extended_kalman_filter/extended_kalman_filter_localization.ipynb
index 8d4c61bb..aa7c5bef 100644
--- a/Localization/extended_kalman_filter/extended_kalman_filter_localization.ipynb
+++ b/Localization/extended_kalman_filter/extended_kalman_filter_localization.ipynb
@@ -162,7 +162,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# Observation Model\n",
+    "### Observation Model\n",
     "\n",
     "The robot can get x-y position infomation from GPS.\n",
     "\n",
@@ -204,7 +204,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# Extented Kalman Filter\n",
+    "### Extented Kalman Filter\n",
     "\n",
     "Localization process using Extendted Kalman Filter:EKF is\n",
     "\n",