1. U.S. Smartphone Use in 2015http://www.pewinternet.org/2015/04/01/us-smartphone-use-in-2015/
2. Gigmag: Improved GPS Could Untether VR and Revolutionize Geolocationhttp://www.gizmag.com/super-accurate-gps/37422/
3. 2014 Federal Radionavigation Plan,2010
4. The Smartphone as a Surveying Tool, FIG Working Week 2013 Environment for Sustainabilityhttp://www.fig.net/resources/proceedings/fig_proceedings/fig2013/papers/ts03c/TS03C_oluropo_6626.pdf
5. Qualcomm: GPS and GLONASS: “Dual-Core” Location for Your Phonehttps://www.qualcomm.com/news/onq/2011/12/15/gps-and-glonass-dual-core-location-your-phone