From the Author Guidelines of the Communications of the ACM
References ... to previous work should be included at the end of the article. References must be ordered alphabetically by first author and numbered. All listed references must be referred to in text by their corresponding number.
Communications Reference Style
Journal:
Parker, R. Lotus copyright protection is turning into a feeding frenzy. Infoworld 12,28 (Jul. 1990), 42-49.
Book:
Hoffman, W.M. and Moore, J.M., Eds. Ethics and the Management of Computer Technology. Oelgeschlager, Gunn and Hain, Cambridge, Mass., 1982.
Proceedings:
Rumbaugh, J.E. Controlling propagation of operations using attributes on Relations. In Proceedings of OOPSLA '86 (Sept. 29-Oct. 2, Portland,Oreg.). ACM/SIGPLAN, New York, 1986, pp. 406-416.