Our Indoor GPS system, position sytem for moving units with 10 mm precision
Why can't GPS be used for indoor positioning? - Redpoint Positioning
The Guide To Indoor Location Services - BlueFletch
GitHub - IndoorLocation/gps-indoor-location-provider-android: Allows the GPS to be used with IndoorLocation to provide a position when the user is outside and no indoor positioning system is in sight.
Oriient: Hassle-free Indoor GPS
Sensors | Free Full-Text | A New Indoor Positioning System Architecture Using GPS Signals