A-Tech 8GB (2x4GB) RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010, Mid 2011, Late 2011), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
Samsung 4GB SODIMM 1333MHz 204-pin, M471B5273DH0-CH9 at Amazon.com