In　dynamic　spectrum　access　systems,　such　as　cognitive　radio　networks,　spectrum　pooling　is　one　of　the　approaches　to　manage　the　available　spectrum　bands　from　different　licensed　networks.　Based　on　the　concept　of　spectrum　pooling,　most　previous　work　focuses　on　the　system　architecture　and　the　design　of　flexible　access　algorithms　and　schemes.　In　this　paper,　a　cooperative　and　distributed　scheme　for　dynamic　internetwork　spectrum　sharing　among　multiple　networks　is　proposed,　taking　into　account　the　spectrum　access　price　and　the　spectrum　efficiency.　Specifically,　the　spectrum　sharing　problem　is　formulated　as　a　restless　bandits　model-based　optimization　system,　which　dramatically　reduces　the　complexity　of　the　scheme　by　allowing　the　spectrum　allocation　scheme　to　be　simply　select　the　network　with　the　lowest　index.　Extensive　simulation　results　illustrate　that　the　proposed　scheme　improves　the　performance　significantly　compared　to　the　existing　scheme　that　ignores　the　distributed　and　cooperative　spectrum　sharing.　©2010　IEEE.