2B. Schilit and M. Theimer. Disseminating active map information to mobile host [J]. Network, IEEE, 1994, 8(5):22-32.
3G. D. Abowd, A. K. Dey, P. J. Brown, et al. Towards a better understanding of context and context-awar- reness[J]. Proceedings of the 1st international sympo- sium on Handbeld and Ubiquitous Computing, 1999, 304-307.
4B. Schilit, N. Adams, R. Want, et al. Context-aware computing applications [-J-]. Mobile Computing Sys- tems and Applications, 1994 : 85- 90.