The theory and practice of no-fly zones, including questions of their legal authorization and financial cost, are reviewed in a newly reissued report from the Congressional Research Service. The report does not reference the current conflict in Syria. See No-Fly Zones: Strategic, Operational, and Legal Considerations for Congress, May 3, 2013.
Some of the other most recent CRS products (all of which are updates today) are these:
The Fair Labor Standards Act (FLSA): An Overview, May 3, 2013
Energy and Water Development: FY2013 Appropriations, April 25, 2013
Nuclear Energy: Overview of Congressional Issues, April 29, 2013