diff --git a/math_differential_calculus.ipynb b/math_differential_calculus.ipynb
index 210ff97..3a2bba2 100644
--- a/math_differential_calculus.ipynb
+++ b/math_differential_calculus.ipynb
@@ -544,7 +544,7 @@
     "id": "Zu6u_8bw7ZUc"
    },
    "source": [
-    "A word about notations: there are several other notations for the derivative that you will find in the litterature:\n",
+    "A word about notations: there are several other notations for the derivative that you will find in the literature:\n",
     "\n",
     "$f'(x) = \\dfrac{\\mathrm{d}f(x)}{\\mathrm{d}x} = \\dfrac{\\mathrm{d}}{\\mathrm{d}x}f(x)$\n",
     "\n",
@@ -1780,7 +1780,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.6"
+   "version": "3.6.1"
   },
   "pycharm": {
    "stem_cell": {