1. Barkhuus, L., Dey, A.: Location-based services for mobile telephony: a study of user’s privacy concerns. In: Proc. of the 9th IFIP TC13 International Conference on Human-Computer Interaction (INTERACT 2003), Zurich, Switzerland (September 2003)
2. D’Roza, T., Bilchev, G.: An overview of location-based services. BT Technology Journal 21(1), 20–27 (2003)
3. Loopt (December 2008), http://www.loopt.com/about/privacy-security
4. Zander, C.: Cia Cell Tower Monitors Local Internet Users’ Wireless Transmissions (September 2007), http://www.send2press.com/newswire/2007-09-0911-003.shtml
5. Chicago Tribune: Rental firm uses GPS in speeding fine, p.9. Associated Press, Chicago (July 2, 2001)