Improvements in the microphone

Improvements in the microphone: No. 311/72.Declared.12/15/1877.Issue 08/02/1884 / "Bella".- [St. Petersburg]: Type.Exped.Zagot.state.papers, 1884. -2 p., 1 l.Il .. -The privilege issued from the Department of Trade and Manufactory in 1884 by the International Bell telephone Company, for improvement in the microphone.Before the text: 72.Ex.: With a handle.litter..I. "Bella", international telephone company. 1.People (collection).Electronic copy source: PBOriginal storage location: VPTB FIPS