Amazon.com: A1417 Battery Only for (Mid 2012 & Early 2013) A1398 MacBook Pro - Replacement Battery for A1398 MacBook Pro 15-inch Retina (Mid 2012, Early 2013 Version) - EMC 2512 or 2673 [11.26V/99Wh] : Electronics
BatPower | A1437 Battery for Late 2012 Apple MacBook Pro 13" Retina A1425 -11.21V/74Wh/6600mAh
MacBook Pro with Retina display review (15-inch) - The Verge