American Telephone and Telegraph Company. Long Lines Dept. (1939). Principles of electricity applied to telephone and telegraph work: A training course text prepared for employees of the Long Lines Department, American Telephone and Telegraph Company, November 1938. s.n.
Chicago-referens (17:e uppl.)American Telephone and Telegraph Company. Long Lines Dept. Principles of Electricity Applied to Telephone and Telegraph Work: A Training Course Text Prepared for Employees of the Long Lines Department, American Telephone and Telegraph Company, November 1938. [New York]: s.n, 1939.
MLA-referens (9:e uppl.)American Telephone and Telegraph Company. Long Lines Dept. Principles of Electricity Applied to Telephone and Telegraph Work: A Training Course Text Prepared for Employees of the Long Lines Department, American Telephone and Telegraph Company, November 1938. s.n, 1939.