R. Ehrenberg, and R. Smith. Pearson/Addison Wesley, Boston, (2009)019: 176890931; Ronald G. Ehrenberg, Robert S. Smith.; Includes bibliographical references and indexes..
X. Yang, L. Liu, N. Vaidya, and F. Zhao. The First Annual International Conference on Mobile and Ubiquitous
Systems: Networking and Services (MOBIQUITOUS), page 114 - 123. (August 2004)