diff --git a/README.md b/README.md
index b91f45a7a..58ccc3e7d 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@
   <a href="https://www.hello-algo.com/">
     <img src="https://www.hello-algo.com/index.assets/btn_read_online_dark.svg" height="45"></a>
   <a href="https://github.com/krahets/hello-algo/releases">
-    <img src="https://www.hello-algo.com/index.assets/btn_download_pdf_dark.svg" height="45"></a>
+    <img src="https://www.hello-algo.com/index.assets/btn_download_pdf_epub_dark.svg" height="45"></a>
 </p>
 
 <p align="center">
diff --git a/docs/index.assets/btn_download_pdf_dark.svg b/docs/index.assets/btn_download_pdf_epub_dark.svg
similarity index 100%
rename from docs/index.assets/btn_download_pdf_dark.svg
rename to docs/index.assets/btn_download_pdf_epub_dark.svg
diff --git a/en/README.md b/en/README.md
index 791605196..db534581f 100644
--- a/en/README.md
+++ b/en/README.md
@@ -13,7 +13,7 @@
   <a href="https://www.hello-algo.com/en/">
     <img src="https://www.hello-algo.com/en/index.assets/btn_read_online_dark.svg" height="45"></a>
   <a href="https://github.com/krahets/hello-algo/releases">
-    <img src="https://www.hello-algo.com/en/index.assets/btn_download_pdf_dark.svg" height="45"></a>
+    <img src="https://www.hello-algo.com/en/index.assets/btn_download_pdf_epub_dark.svg" height="45"></a>
 </p>
 
 <p align="center">
diff --git a/en/docs/index.assets/btn_download_pdf_dark.svg b/en/docs/index.assets/btn_download_pdf_epub_dark.svg
similarity index 100%
rename from en/docs/index.assets/btn_download_pdf_dark.svg
rename to en/docs/index.assets/btn_download_pdf_epub_dark.svg
diff --git a/ja/docs/index.assets/btn_chinese_edition.svg b/ja/docs/index.assets/btn_chinese_edition.svg
deleted file mode 100644
index 1d43e5738..000000000
--- a/ja/docs/index.assets/btn_chinese_edition.svg
+++ /dev/null
@@ -1 +0,0 @@
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\ No newline at end of file
diff --git a/ja/docs/index.assets/btn_chinese_edition_dark.svg b/ja/docs/index.assets/btn_chinese_edition_dark.svg
deleted file mode 100644
index e622663ba..000000000
--- a/ja/docs/index.assets/btn_chinese_edition_dark.svg
+++ /dev/null
@@ -1 +0,0 @@
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diff --git a/ja/docs/index.assets/btn_download_pdf.svg b/ja/docs/index.assets/btn_download_pdf.svg
deleted file mode 100644
index ed236a077..000000000
--- a/ja/docs/index.assets/btn_download_pdf.svg
+++ /dev/null
@@ -1 +0,0 @@
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diff --git a/ja/docs/index.assets/btn_download_pdf_dark.svg b/ja/docs/index.assets/btn_download_pdf_dark.svg
deleted file mode 100644
index 308cfeda0..000000000
--- a/ja/docs/index.assets/btn_download_pdf_dark.svg
+++ /dev/null
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diff --git a/ja/docs/index.assets/btn_download_pdf_epub_dark.svg b/ja/docs/index.assets/btn_download_pdf_epub_dark.svg
new file mode 100644
index 000000000..20892d60a
--- /dev/null
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diff --git a/ja/docs/index.assets/btn_read_online.svg b/ja/docs/index.assets/btn_read_online.svg
deleted file mode 100644
index a2500e44f..000000000
--- a/ja/docs/index.assets/btn_read_online.svg
+++ /dev/null
@@ -1 +0,0 @@
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diff --git a/zh-hant/README.md b/zh-hant/README.md
index 27e43b35d..bfccef360 100644
--- a/zh-hant/README.md
+++ b/zh-hant/README.md
@@ -13,7 +13,7 @@
   <a href="https://www.hello-algo.com/zh-hant/">
     <img src="https://www.hello-algo.com/zh-hant/index.assets/btn_read_online_dark.svg" height="45"></a>
   <a href="https://github.com/krahets/hello-algo/releases">
-    <img src="https://www.hello-algo.com/zh-hant/index.assets/btn_download_pdf_dark.svg" height="45"></a>
+    <img src="https://www.hello-algo.com/zh-hant/index.assets/btn_download_pdf_epub_dark.svg" height="45"></a>
 </p>
 
 <p align="center">
diff --git a/zh-hant/docs/index.assets/btn_download_pdf_dark.svg b/zh-hant/docs/index.assets/btn_download_pdf_epub_dark.svg
similarity index 100%
rename from zh-hant/docs/index.assets/btn_download_pdf_dark.svg
rename to zh-hant/docs/index.assets/btn_download_pdf_epub_dark.svg