Federal subsidies for Essential Air Services in the United States
Congressional Research Service
2015
<a rel="nofollow" class="external free" href="http://www.fas.org/sgp/crs/misc/R44176.pdf">http://www.fas.org/sgp/crs/misc/R44176.pdf</a>,  Essential Air Service (EAS) Report by the Congressional Research Service, September 3, 2015