diff --git a/doc/example/chap/chap1.tex b/doc/example/chap/chap1.tex
index 3d606d5..691206c 100644
--- a/doc/example/chap/chap1.tex
+++ b/doc/example/chap/chap1.tex
@@ -5,5 +5,5 @@
 \chapter{章节}
 
 % 三个命令分别产生未格式化的、带方括号的和上标且带方括号的引用标记。
-测试一下：\cite{test}，\parencite{test}，\supercite{test}。
+测试一下：\cite{test-en}，\parencite{test-zh}，\supercite{test-en, test-zh}。
 
diff --git a/doc/example/thesis.bib b/doc/example/thesis.bib
index 0ea3ff7..4e8d0fd 100644
--- a/doc/example/thesis.bib
+++ b/doc/example/thesis.bib
@@ -1,10 +1,20 @@
 % vim:ts=4:sw=4
 
-@article{test,
+@article{test-en,
 	author = {Author},
 	title = {Title},
 	type = {J},
 	journal = {Journal},
 	date = {2014-04-01},
+	language = {english},
+}
+
+@article{test-zh,
+	author = {作者},
+	title = {标题},
+	type = {J},
+	journal = {期刊},
+	date = {2014-04-01},
+	language = {chinese},
 }
 
diff --git a/doc/readme/pkuthss.bib b/doc/readme/pkuthss.bib
index 2d3312f..822bd9a 100644
--- a/doc/readme/pkuthss.bib
+++ b/doc/readme/pkuthss.bib
@@ -7,6 +7,7 @@
 	date = {2013-10-18},
 	url = {http://mirror.ctan.org/biblio/biber/},
 	urldate = {2014-05-24},
+	language = {english},
 }
 
 @online{biblatex,
@@ -16,6 +17,7 @@
 	date = {2013-11-25},
 	url = {http://mirror.ctan.org/macros/latex/exptl/biblatex/},
 	urldate = {2014-05-24},
+	language = {english},
 }
 
 @online{biblatex-caspervector,
@@ -25,7 +27,7 @@
 	date = {2014-05-24},
 	url = {https://caspervector-dist.googlecode.com/git/biblatex-caspervector/biblatex-caspervector-0.2.0.zip},
 	urldate = {2014-05-24},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{caption,
@@ -35,6 +37,7 @@
 	date = {2011-11-02},
 	url = {http://mirror.ctan.org/macros/latex/contrib/caption},
 	urldate = {2013-06-03},
+	language = {english},
 }
 
 @online{ctex,
@@ -44,7 +47,7 @@
 	date = {2011-03-11},
 	url = {http://mirror.ctan.org/language/chinese/ctex/},
 	urldate = {2012-08-01},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{ctex-faq,
@@ -54,7 +57,7 @@
 	date = {2007-01-30},
 	url = {http://mirror.ctan.org/info/ctex-faq/},
 	urldate = {2012-08-01},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{enumitem,
@@ -64,6 +67,7 @@
 	date = {2011-09-28},
 	url = {http://mirror.ctan.org/macros/latex/contrib/enumitem/},
 	urldate = {2012-08-01},
+	language = {english},
 }
 
 @online{fancyhdr,
@@ -73,6 +77,7 @@
 	date = {2004-03-02},
 	url = {http://mirror.ctan.org/macros/latex/contrib/fancyhdr/},
 	urldate = {2012-08-01},
+	language = {english},
 }
 
 @online{footmisc,
@@ -82,6 +87,7 @@
 	date = {2011-07-06},
 	url = {http://mirror.ctan.org/macros/latex/contrib/footmisc/},
 	urldate = {2012-08-01},
+	language = {english},
 }
 
 @online{geometry,
@@ -91,6 +97,7 @@
 	date = {2010-09-12},
 	url = {http://mirror.ctan.org/macros/latex/contrib/geometry/},
 	urldate = {2012-08-01},
+	language = {english},
 }
 
 @online{graphicx,
@@ -100,6 +107,7 @@
 	date = {2005-11-14},
 	url = {http://mirror.ctan.org/macros/latex/required/graphics/},
 	urldate = {2012-08-01},
+	language = {english},
 }
 
 @online{hyperref,
@@ -109,6 +117,7 @@
 	date = {2012-05-13},
 	url = {http://mirror.ctan.org/macros/latex/contrib/hyperref/},
 	urldate = {2012-08-01},
+	language = {english},
 }
 
 @online{xCJK2uni,
@@ -118,7 +127,7 @@
 	date = {2013-08-17},
 	url = {http://mirror.ctan.org/macros/latex/contrib/xcjk2uni/},
 	urldate = {2014-05-10},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{dypang,
@@ -128,7 +137,7 @@
 	date = {2005-04-05},
 	url = {http://bdwm.net/a.php?b/Thesis/M.1112645491.A/D10F612.rar},
 	urldate = {2012-08-01},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{FerretL,
@@ -138,7 +147,7 @@
 	date = {2007-03-27},
 	url = {http://bdwm.net/a.php?b/Thesis/M.1174982168.A/4270722.rar},
 	urldate = {2012-08-01},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{lwolf,
@@ -148,7 +157,7 @@
 	date = {2007-05-15},
 	url = {http://bdwm.net/a.php?b/MathTools/M.1179239165.A/5A2D5A2.rar},
 	urldate = {2012-08-01},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{Langpku,
@@ -158,7 +167,7 @@
 	date = {2007-06-01},
 	url = {http://bdwm.net/a.php?b/MathTools/M.1180676700.A/DBB7810.zip},
 	urldate = {2012-08-01},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{solvethis,
@@ -168,7 +177,7 @@
 	date = {2008-03-13},
 	url = {http://bdwm.net/a.php?b/Thesis/M.1205377509.A/9413ED2.rar},
 	urldate = {2012-08-01},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{pku-copyright,
@@ -178,7 +187,7 @@
 	year = {2014},
 	url = {http://grs.pku.edu.cn/document/20140416145103446514.doc},
 	urldate = {2014-05-24},
-	userf = {zh},
+	language = {chinese},
 }
 
 @online{pku-originauth,
@@ -188,7 +197,7 @@
 	year = {2014},
 	url = {http://grs.pku.edu.cn/document/20140416145000135438.doc},
 	urldate = {2014-05-24},
-	userf = {zh},
+	language = {chinese},
 }
 
 @incollection{pku-thesisstyle,
@@ -202,6 +211,6 @@
 	pages = {30-35},
 	url = {http://grs.pku.edu.cn/document/20131031200524521428.pdf},
 	urldate = {2014-05-24},
-	userf = {zh},
+	language = {chinese},
 }