diff --git a/README.md b/README.md
index bd3a9e1..5793481 100644
--- a/README.md
+++ b/README.md
@@ -64,6 +64,7 @@ you can insert raw html using the corresponding `.gmo` syntax: the contents of a
 # references
 
 * [EPUB - Wikipedia](https://en.wikipedia.org/wiki/EPUB#Implementation)
+* [EPUB 3.2](https://www.w3.org/publishing/epub3/)
 * [Gempub](https://codeberg.org/oppenlab/gempub)
 
 # license