2ZANDBERGEN P A. Accuracy of iPhone Locations:A Comparison of Assisted GPS, WiFi and Cellular Positioning[J]. Transactions in GIS, 2009, 13(S1):5-25.
3ZANDBERGEN P A, BARBEAU S J. Positional Accuracy of Assisted GPS Data from High-sensitivity GPS-enabled Mobile Phones[J]. Journal of Navigation, 2011, 64(3):381-399.