diff --git a/index.html b/index.html
index e9b4078..0629bfe 100644
--- a/index.html
+++ b/index.html
@@ -1717,6 +1717,7 @@ <h3><a href="https://github.com/lib-pku/libpku/raw/master/%E9%80%9A%E9%80%89%E8%
 <h4><a href="https://github.com/lib-pku/libpku/raw/master/%E9%80%9A%E9%80%89%E8%AF%BE%2FF%2F%E8%87%AA%E7%84%B6%E4%BF%9D%E6%8A%A4%E5%AD%A6">自然保护学</a></h4>
 <p><a href="https://github.com/lib-pku/libpku/raw/master/%E9%80%9A%E9%80%89%E8%AF%BE%2FF%2F%E8%87%AA%E7%84%B6%E4%BF%9D%E6%8A%A4%E5%AD%A6%2F%E8%87%AA%E7%84%B6%E4%BF%9D%E6%8A%A4%E5%AD%A6%E6%80%9D%E8%80%83%E9%A2%98%E6%95%B4%E7%90%86.pdf">自然保护学思考题整理.pdf</a>
 <a href="https://github.com/lib-pku/libpku/raw/master/%E9%80%9A%E9%80%89%E8%AF%BE%2FF%2F%E8%87%AA%E7%84%B6%E4%BF%9D%E6%8A%A4%E5%AD%A6%2F%E8%87%AA%E7%84%B6%E4%BF%9D%E6%8A%A4%E5%AD%A6%E6%9C%9F%E6%9C%AB%E6%95%B4%E7%90%86.doc">自然保护学期末整理.doc</a></p>
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