diff --git a/TODO.md b/TODO.md
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--- a/TODO.md
+++ b/TODO.md
@@ -1,5 +1,7 @@
 # TODO
 
+https://zhuanlan.zhihu.com/p/33778843
+
 ## Vlpp
 
 * Regex supports UTF-16 (instead of UCS-2) on MSVC.