enciclopedias

http://books.google.com.mx/books?id=DIECAAAAQAAJ&pg=PA117&dq=sordomudos+lenguaje&ei=53cNS7qzNoXUNKOeiPAE#v=onepage&q=sordomudos%20lenguaje&f=false


http://books.google.com.mx/books?id=PCpWVR2gvL4C&pg=PA189&dq=sordomudos+lenguaje&lr=&ei=yngNS62XHoSyNJ3YqI4B#v=onepage&q=sordomudos%20lenguaje&f=false