diff --git a/zjuthesis.tex b/zjuthesis.tex
index bb9f909b..400527c0 100644
--- a/zjuthesis.tex
+++ b/zjuthesis.tex
@@ -165,11 +165,11 @@
     \inputbody{post}
 }
 
-\begin{document}
-
 \addbibresource{body/ref.bib}
 % * add these line to enable ref suggest in vscode.
 
+\begin{document}
+
 \ifthenelse{\equal{\Degree}{undergraduate}}
 {
     \inputundergraduate{}