diff --git a/virtual.mdwn b/virtual.mdwn
index 5daac36532713744d44870ab15a6daf8ee4db270..13f5d0efe675cf71986c8650825c34fb3b2c3f1b 100644
--- a/virtual.mdwn
+++ b/virtual.mdwn
@@ -11,3 +11,9 @@ Desktop
 
 * [plymouth - Debian Wiki](https://wiki.debian.org/plymouth)
 * Additional package: [virtualbox-guest-x11](https://packages.debian.org/stable/virtualbox-guest-x11).
+
+References
+----------
+
+* [Marco Carnut: Ambiente "Auto-Limpante" via Virtualização Ultra-Leve Descartável - Tempest Blog](http://blog.tempest.com.br/marco-carnut/ambiente-auto-limpante-via-virtualizacao-ultra-leve-descartavel.html).
+* [Subgraph OS and Mail](https://subgraph.com/sgos/index.en.html).