APA (7th ed.) Citation

E, M. T. (1990). Telephone line security system.

Chicago Style (17th ed.) Citation

E, MURRAY; THORNTONE. Telephone Line Security System. 1990.

MLA (9th ed.) Citation

E, MURRAY; THORNTONE. Telephone Line Security System. 1990.

Warning: These citations may not always be 100% accurate.