Edmund Edward Fournier d'Albe

• http://en.wikipedia.org/wiki/Edmund_Edward_Fournier_d'Albe
• http://en.wikipedia.org/wiki/Optophone
• http://archive.org/details/philtrans02205130
• http://en.wikisource.org/wiki/1922_Encyclop%C3%A6dia_Britannica/Optophone