MacBook Pro 15" Unibody Early 2011 Battery Replacement - iFixit Repair Guide
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Amazon.com: A1322 Battery for A1278 Apple MacBook pro 13 inch Mid 2012 Early 2011 Late 2011 Mid 2010 2009 with 6000mAh Newer Tech (MC374LL/A MB990LL/A MB991LL/A MC700LL/A MD313LL/A MD101LL/A MD102LL/A Battery) :
Replace Battery for Apple MacBook Pro 13'' 13 inch A1278 A1322 mid 2009-2012 | eBay
MacBook Pro 15" Unibody (Early 2011-Mid 2012) Battery - iFixit Store
Amazon.com: iFixit A1398 A1618 Battery for MacBook Pro 15" Retina (Mid 2015) - Fix Kit : Electronics
How to Replace the Battery in a 13-inch MacBook Pro 2011 (Updated) | Macbook pro 2012, Macbook pro 2011, Macbook
How to replace the battery in a mid-2012 Macbook Pro | David Artiss
Amazon.com: iFixit Battery Compatible with MacBook Air 11" (Mid 2011-Early 2015) : Electronics