1. Merriam‐WebsterOnline dictionary:http://www.merriam‐webster.com/
2. WAAS T & E Team WilliamJ.Hughes Technical Center “Global Positioning System (GPS) Standard Positioning Service (SPS) Performance Analysis Report ” Report #93 submitted to FAA GPS Product Team April 30 2016. Can be found at:http://www.nstb.tc.faa.gov/reports/PAN93_0416.pdf
3. Leveson I. “The Economic Value of GPS: Preliminary Assessment ” Presentation to the National Space‐Based Positioning Navigation and Timing Advisory Board Meeting June2015. Can be found at:http://www.gps.gov/governance/advisory/meetings/2015‐06/leveson.pdf
4. Global Positioning System Standard Positioning Service Performance Analysis Report Report Number 88 Reporting Period 1 October–3 December 2014 William J Hughes Technical Center WAAS T&E team Atlantic City International Airport New Jersey January 31 2015.