diff --git a/.copyright.hook b/.copyright.hook
index 3be6d0ae5bf352aa08ee44ab2144670f1bf03510..1b0acacb97a1b3059fcc88fb44b6168fa0419473 100644
--- a/.copyright.hook
+++ b/.copyright.hook
@@ -1,6 +1,5 @@
 from __future__ import absolute_import
 from __future__ import print_function
-from __future__ import unicode_literals
 
 import argparse
 import io, re
diff --git a/docs/conf.py b/docs/conf.py
index 2cb758d2048abb26a88f5e5d43ca1e168cd25f19..29f697d1db5fc60304f1da625ed92cf14f2f819b 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -107,3 +107,31 @@ latex_use_xindy = False
 latex_elements = {
     'preamble': '\\usepackage[UTF8]{ctex}\n',
 }
+
+latex_elements = {
+    # The paper size ('letterpaper' or 'a4paper').
+    #'papersize': 'letterpaper',
+
+    # The font size ('10pt', '11pt' or '12pt').
+    #'pointsize': '10pt',
+
+    # Additional stuff for the LaTeX preamble.
+    #'preamble': '',
+    'preamble':
+    r'''
+    \hypersetup{unicode=true}
+    \usepackage{CJKutf8}
+    \DeclareUnicodeCharacter{00A0}{\nobreakspace}
+    \DeclareUnicodeCharacter{2203}{\ensuremath{\exists}}
+    \DeclareUnicodeCharacter{2200}{\ensuremath{\forall}}
+    \DeclareUnicodeCharacter{2286}{\ensuremath{\subseteq}}
+    \DeclareUnicodeCharacter{2713}{x}
+    \DeclareUnicodeCharacter{27FA}{\ensuremath{\Longleftrightarrow}}
+    \DeclareUnicodeCharacter{221A}{\ensuremath{\sqrt{}}}
+    \DeclareUnicodeCharacter{221B}{\ensuremath{\sqrt[3]{}}}
+    \DeclareUnicodeCharacter{2295}{\ensuremath{\oplus}}
+    \DeclareUnicodeCharacter{2297}{\ensuremath{\otimes}}
+    \begin{CJK}{UTF8}{gbsn}
+    \AtEndDocument{\end{CJK}}
+    ''',
+}