07/10/1878 [Supplied day] Scientific American -- Articles
(Edison, Thomas Alva) Multiple telegraphy (duplex, quadruplex); Telephone [Document Within a Document]
[MBSB1]  Special Collections Series -- Charles Batchelor Collection -- Scrapbooks: Cat. 1240 (1876-1878)
[MBSB10763X1; TAEM 94:277]
Courtesy of Thomas Edison National Historical Park.