Adamanta 16GB (2x8GB) Memory Upgrade Compatible for Apple Mid 2010, Early 2011, Mid 2011, Late 2011 iMac, MacBook Pro, Mac Mini DDR3 1333Mhz PC3-10600 SODIMM 2Rx8 CL9 1.5v Module RAM at Amazon.com
Original apple MacBook Pro 4gb ram (2x2gb) from early 2011 MacBook Pro | eBay
MacBook Pro 13" Unibody Early 2011 RAM Replacement - iFixit Repair Guide
hardware - Would this memory work on a MacBook Pro (17-inch, Early 2011)? - Ask Different
Upgrade Your Macbook Pro (SSD Upgrade, RAM Upgrade, Optical Drive Bay Adapter) - YouTube