United States. General Accounting Office. Aviation Infrastructure: Feasibility of Using Alternate Means to Satisfy Requirements of Alaska National Airspace System Interfacility Communications System (ANICS) Phase II, text, September 6, 2000; (https://digital.library.unt.edu/ark:/67531/metadc297771/m1/1/: accessed September 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .