Thomas King Thomas Haenselmann Wolfgang Effelsberg On-demand fingerprint selection for 802.11-based positioning systems. 1-8 2008 WOWMOM http://dx.doi.org/10.1109/WOWMOM.2008.4594839 conf/wowmom/2008 db/conf/wowmom/wowmom2008.html#KingHE08