Horatio Nelson Powers. “Phonogram from Horatio Nelson Powers to George Edward Gouraud, Thomas Alva Edison, June 16th, 1888.” _Edison Papers Digital Edition_. 7 Nov. 2019.

Horatio Nelson Powers. “Phonogram from Horatio Nelson Powers to George Edward Gouraud, Thomas Alva Edison, June 16th, 1888.” _Edison Papers Digital Edition_. 7 Nov. 2019.