1 янв 1950 г. - SOURCES

Описание:

Berquist, Lisa. “Timeline.” The Telecommunications History Group, Inc., 1995, www.telcomhistory.org/timeline.shtml.

Hochfelder, David. “Alexander Graham Bell.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 23 June 2017, www.britannica.com/biography/Alexander-Graham-Bell.

Wilbraham, Antony C., et al. Pearson Chemistry. Pearson, 2017.

Hur, Johnson. “History of the Telephone.” From The 1880s To Current Time, 5 Sept. 2017, bebusinessed.com/history/history-of-the-telephone/.