@BOOK{NAP4920, author = "National Research Council", title = "The Global Positioning System: A Shared National Asset", isbn = "978-0-309-05283-2", doi = "10.17226/4920", abstract = "The Global Positioning System (GPS) is a satellite-based navigation system that was originally designed for the U.S. military. However, the number of civilian GPS users now exceeds the military users, and many commercial markets have emerged. This book identifies technical improvements that would enhance military, civilian, and commercial use of the GPS. Several technical improvements are recommended that could be made to enhance the overall system performance.", url = "https://nap.nationalacademies.org/catalog/4920/the-global-positioning-system-a-shared-national-asset", year = 1995, publisher = "The National Academies Press", address = "Washington, DC" }