diff --git a/01.preface.ipynb b/01.preface.ipynb
index 2208b1cec..2a6860751 100644
--- a/01.preface.ipynb
+++ b/01.preface.ipynb
@@ -206,7 +206,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.1"
+   "version": "3.7.3"
   }
  },
  "nbformat": 4,
diff --git a/Part.3.B.1.classes-1.ipynb b/Part.3.B.1.classes-1.ipynb
index dc06986dc..498eff3be 100644
--- a/Part.3.B.1.classes-1.ipynb
+++ b/Part.3.B.1.classes-1.ipynb
@@ -38,7 +38,7 @@
     "\n",
     "但是，从另外一个角度，反对 OOP 的人群中，牛人比例更高 —— 这也是个看起来颇为吊诡的事实。\n",
     "\n",
-    "比如，Erlang 的发明者，[Joe Armstrong](https://en.wikipedia.org/wiki/Joe_Armstrong_(programmer) 就很讨厌 OOP，觉得它效率低下。他用的类比也确实令人忍俊不禁，说得也挺准的：\n",
+    "比如，Erlang 的发明者，[Joe Armstrong](https://en.wikipedia.org/wiki/Joe_Armstrong_(programmer)) 就很讨厌 OOP，觉得它效率低下。他用的类比也确实令人忍俊不禁，说得也挺准的：\n",
     "\n",
     "> 支持 OOP 的语言的问题在于，它们总是随身携带着一堆并不明确的环境 —— 你明明只不过想要个香蕉，可你所获得的是一个大猩猩手里拿着香蕉…… 以及那大猩猩身后的整个丛林！<br /> —— [Coders at Work](http://www.codersatwork.com)\n",
     "\n",