A-Tech 4GB 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 Module at Amazon.com
4GB RAM Upgrade Kit (2 x 2GB) Apple Macbooks Laptops 2011 2012 DDR3 PC3 10600s | eBay
OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com
Crucial 4GB DDR3L-1333 SODIMM Memory for Mac | CT4G3S1339M | Crucial.com
RAM upgrade and/or SSD drive – what's the benefit?
RAM upgrade and/or SSD drive – what's the benefit?
How to know what kind of RAM my laptop uses - Quora