Royal Academy of the Spanish Language
http://www.diccionarios.com/
http://www.idiomax.com/es/online-dictionary.aspx
http://www.idiomax.com/online-dictionary.aspx
Computing dictionary: http://www.alegsa.com.ar/Diccionario/diccionario.php
Articles:
The larynx and the voice: http://www.laringeyvoz.com/laringeyvoz.htm
Books:
