diff --git a/1000-hours/sounds-of-english/15-mn.md b/1000-hours/sounds-of-english/15-mn.md
index c14b6b5f6..e97ada0ef 100644
--- a/1000-hours/sounds-of-english/15-mn.md
+++ b/1000-hours/sounds-of-english/15-mn.md
@@ -21,4 +21,4 @@
 
 有些词典会直接将 *didn't* 标注为 `/ˈdɪdənt/`，将 *wouldn't* 标注为 `/ˈwʊdənt/`，将 *rhythm* 标注成 `/ˈrɪðəm/`…… 但是，音节辅音内的元音音素，更准确地讲，更接近 `ɤ`（[2.2.1](13-pbmnfkgh)）而不是 `ə` —— 这个细微差异，竟然会使美国人轻易地听出外国口音[^1]。
 
-[^1]: *Manual of Amewrican English Pronuciation*, 4th edition, by Clifford H. Prator, Jr. Betty Wallace Robinett.
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+[^1]: *Manual of Amewrican English Pronuciation*, 4th edition, by Clifford H. Prator, Jr. Betty Wallace Robinett. Page 118.
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