(en) Plaquette op Franklin School in Washington DC. Gearchiveerd op 17-09-2008. Geraadpleegd op 2008. “From the top floor of this building was sent on june 3, 1880 over a beam of light to 1325 L street the first wireless telephone message in the history of the world. The apparatus used in sending the message was the photophone invented by Alexander Graham Bell, inventor of the telephone. This plaque was placed here by Alexander Graham Bell Chapter Telephone Pioneers of America. March 3, 1947, the centennial of Dr. Bell's birth.”
