diff --git a/free-programming-books.md b/free-programming-books.md
index 9dacad28dd5b44c970b7adfb170b8bae298331ef..4f8e8183ae51889c34045009e1df6bb9670be332 100644
--- a/free-programming-books.md
+++ b/free-programming-books.md
@@ -34,6 +34,7 @@
 * [DTrace](#dtrace)
 * [Elasticsearch](#elasticsearch)
 * [Elixir](#elixir)
+  * [Phoenix](#phoenix)
 * [Emacs](#emacs)
 * [Embedded Systems](#embedded-systems)
 * [Erlang](#erlang)
@@ -978,6 +979,11 @@
 * [Learning Elixir](http://learningelixir.joekain.com) - Joseph Kain Blog (HTML)
 
 
+#### Phoenix
+
+* [Versioned APIs with Phoenix](http://elviovicosa.com/books/versioned-apis-with-phoenix) - Elvio Vicosa (PDF)
+
+
 ### Emacs
 
 * [An Introduction to Programming in Emacs Lisp, 3rd Edition](https://www.gnu.org/software/emacs/manual/html_node/eintr/index.html)