Jelaskan Rujukan dari Nombor telefon kecemasan dalam bahasa melayu

Cutler, David M. (2000). The Changing Hospital Industry: Comparing Not-for-Profit and For-Profit. Chicago: University of Chicago Press. . . p. 118.

Mobile Reference (2007). "Chapter: History of emergency services numbers"

BBC Seriously podcast "999 - Which Service Do You Require?" 30 June 2017