diff --git a/free-programming-books-es.md b/free-programming-books-es.md
index ad440f30..7a7cbaa8 100644
--- a/free-programming-books-es.md
+++ b/free-programming-books-es.md
@@ -20,6 +20,7 @@
 * [Git](#git)
 * [Haskell](#haskell)
 * [JavaScript](#javascript)
+    * [D3](#d3js)
     * [jQuery](#jquery)
     * [node.js](#nodejs)
 * [Java](#java)