diff --git a/arrays-strings/compress.ipynb b/arrays-strings/compress.ipynb
index f27d9c2..6c3eea1 100644
--- a/arrays-strings/compress.ipynb
+++ b/arrays-strings/compress.ipynb
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -231,7 +238,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.9"
+   "version": "2.7.10"
   }
  },
  "nbformat": 4,
diff --git a/arrays-strings/hash-map.ipynb b/arrays-strings/hash-map.ipynb
index ccbb702..ada0f25 100644
--- a/arrays-strings/hash-map.ipynb
+++ b/arrays-strings/hash-map.ipynb
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -139,9 +146,6 @@
    },
    "outputs": [],
    "source": [
-    "#* get and set on an empty hash\n",
-    "#* get and set on a non empty hash\n",
-    "#* get and set on a hash index with collision\n",
     "table_size = 10\n",
     "hash_table = HashTable(table_size)\n",
     "print(\"get on an empty hash table index\")\n",
@@ -184,7 +188,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.9"
+   "version": "2.7.10"
   }
  },
  "nbformat": 4,
diff --git a/arrays-strings/permutation.ipynb b/arrays-strings/permutation.ipynb
index cdacf65..4e20b35 100644
--- a/arrays-strings/permutation.ipynb
+++ b/arrays-strings/permutation.ipynb
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -164,7 +171,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.9"
+   "version": "2.7.10"
   }
  },
  "nbformat": 4,
diff --git a/arrays-strings/replace_char.ipynb b/arrays-strings/replace_char.ipynb
index 69491d8..e8b8605 100644
--- a/arrays-strings/replace_char.ipynb
+++ b/arrays-strings/replace_char.ipynb
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -151,7 +158,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.9"
+   "version": "2.7.10"
   }
  },
  "nbformat": 4,
diff --git a/arrays-strings/reverse_string.ipynb b/arrays-strings/reverse_string.ipynb
index 9d931c6..291e0ba 100644
--- a/arrays-strings/reverse_string.ipynb
+++ b/arrays-strings/reverse_string.ipynb
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -154,7 +161,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.9"
+   "version": "2.7.10"
   }
  },
  "nbformat": 4,
diff --git a/arrays-strings/rotation.ipynb b/arrays-strings/rotation.ipynb
index 19d05a6..39959db 100644
--- a/arrays-strings/rotation.ipynb
+++ b/arrays-strings/rotation.ipynb
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -108,7 +115,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.9"
+   "version": "2.7.10"
   }
  },
  "nbformat": 4,
diff --git a/arrays-strings/unique_chars.ipynb b/arrays-strings/unique_chars.ipynb
index 5204b0b..f8e7618 100644
--- a/arrays-strings/unique_chars.ipynb
+++ b/arrays-strings/unique_chars.ipynb
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -186,7 +193,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.9"
+   "version": "2.7.10"
   }
  },
  "nbformat": 4,