Are any online resources available for ATC recordings?
LiveATC is probably your best shot. The quality you'll get on the stream depends on where the receiver is setup. Since aircraft communications are in VHF or UHF (military) reception is basically within line-of-sight range. This is why often you'll hear the aircraft side of the conversation without hearing ATC.

I would just browse the various streams on LiveATC until you find a good one. OR, if you're near an airport, set up your own receiver!