diff --git a/01_elements_01_review.ipynb b/01_elements_01_review.ipynb
index 68ae395..9c398f7 100644
--- a/01_elements_01_review.ipynb
+++ b/01_elements_01_review.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 1: Elements of a Program"
    ]
   },
diff --git a/01_elements_02_exercises.ipynb b/01_elements_02_exercises.ipynb
index 7cdd98f..fb7bc75 100644
--- a/01_elements_02_exercises.ipynb
+++ b/01_elements_02_exercises.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 1: Elements of a Program"
    ]
   },
diff --git a/03_conditionals_01_review.ipynb b/03_conditionals_01_review.ipynb
index 57a706e..5a5da9d 100644
--- a/03_conditionals_01_review.ipynb
+++ b/03_conditionals_01_review.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 3: Conditionals & Exceptions"
    ]
   },
diff --git a/03_conditionals_02_exercises.ipynb b/03_conditionals_02_exercises.ipynb
index c8870ce..510b8cb 100644
--- a/03_conditionals_02_exercises.ipynb
+++ b/03_conditionals_02_exercises.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 3: Conditionals & Exceptions"
    ]
   },
diff --git a/04_iteration_01_review.ipynb b/04_iteration_01_review.ipynb
index de4a566..283a72a 100644
--- a/04_iteration_01_review.ipynb
+++ b/04_iteration_01_review.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 4: Recursion & Looping"
    ]
   },
diff --git a/04_iteration_02_exercises.ipynb b/04_iteration_02_exercises.ipynb
index 4f819ca..d795aa5 100644
--- a/04_iteration_02_exercises.ipynb
+++ b/04_iteration_02_exercises.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 4: Recursion & Looping"
    ]
   },
diff --git a/04_iteration_03_exercises.ipynb b/04_iteration_03_exercises.ipynb
index b44c488..7d69c33 100644
--- a/04_iteration_03_exercises.ipynb
+++ b/04_iteration_03_exercises.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 4: Recursion & Looping"
    ]
   },
diff --git a/05_numbers_01_review.ipynb b/05_numbers_01_review.ipynb
index cb297bb..7b3ac58 100644
--- a/05_numbers_01_review.ipynb
+++ b/05_numbers_01_review.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 5: Numbers & Bits"
    ]
   },
diff --git a/06_text_01_review.ipynb b/06_text_01_review.ipynb
index cbe5d80..8727868 100644
--- a/06_text_01_review.ipynb
+++ b/06_text_01_review.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 6: Text & Bytes"
    ]
   },
diff --git a/06_text_02_exercises.ipynb b/06_text_02_exercises.ipynb
index 92df25a..d488f52 100644
--- a/06_text_02_exercises.ipynb
+++ b/06_text_02_exercises.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 6: Text & Bytes"
    ]
   },
diff --git a/07_sequences_01_review.ipynb b/07_sequences_01_review.ipynb
index de51edc..7e9e5da 100644
--- a/07_sequences_01_review.ipynb
+++ b/07_sequences_01_review.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 7: Sequential Data"
    ]
   },
diff --git a/07_sequences_02_exercises.ipynb b/07_sequences_02_exercises.ipynb
index 575c9c9..b8d0a7b 100644
--- a/07_sequences_02_exercises.ipynb
+++ b/07_sequences_02_exercises.ipynb
@@ -4,7 +4,6 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "\n",
     "# Chapter 7: Sequential Data"
    ]
   },
@@ -741,7 +740,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "**Side Note**: Above, we make `product()` work with a single *collection* type argument instead of a *sequence* type to keep it more generic: For example, we can pass in a `set` object, like `{2, 5, 10}` below, and `product()` continues to work correctly. The `set` type is introducted in [Chapter 8](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/master/08_mappings_00_lecture.ipynb#The-set-Type), and one essential difference to the `list` type is that objects of type `set` have *no* order regarding their elements. So, even though `[2, 5, 10]` and `{2, 5, 10}` look almost the same, the order implied in the literal notation gets lost in memory!"
+    "**Side Note**: Above, we make `product()` work with a single *collection* type argument instead of a *sequence* type to keep it more generic: For example, we can pass in a `set` object, like `{2, 5, 10}` below, and `product()` continues to work correctly. The `set` type is introducted in [Chapter 9](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/master/09_mappings_00_lecture.ipynb#The-set-Type), and one essential difference to the `list` type is that objects of type `set` have *no* order regarding their elements. So, even though `[2, 5, 10]` and `{2, 5, 10}` look almost the same, the order implied in the literal notation gets lost in memory!"
    ]
   },
   {