Maxboost iPhone 4S Battery Case/iPhone 4 Battery Case (1900mAH, Fits All Versions of Apple iPhone 4 & 4S) - Detachable Battery Charger Case External Rechargeable Battery Pack Charging Power Case | Amazon
iPhone 4S: why has standby time dropped? | Technology | theguardian.com
Replacement For iPhone 4S Battery
Apple iPhone 4S - Charge the battery - AT&T
Testing the iPhone 4S' battery life - CNET
Apple iPhone 4S battery test is complete, here go the results [TEST]