G. Buscher, A. Dengel, and L. van Elst. SIGIR '08: Proceedings of the 31st Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, Singapore, page 387-394. (2008)
B. Brandherm, J. Haupert, A. Kröner, M. Schmitz, and F. Lehmann. PerCom 2010 Workshops: Proceedings of the 8th Annual IEEE International Conference on Pervasive Computing and Communications Workshops, Mannheim, Germany, page 768-771. (2010)