8GB RAM Upgrade for 2011 MacBook Pro & Mac Mini Core i5 & i7 – $34 | OSXDaily
How to Upgrade MacBook Pro RAM (2009, 2010, 2011, 2012): EveryMac.com
MacBook Pro 15" Unibody Early 2011 RAM Replacement - iFixit Repair Guide
MacBook Pro: How to remove or install memory - Apple Support
A-Tech 16GB (2x8GB) RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
Apple MacBook Pro Late 2011 8GB Memory & SSD Upgrade - YouTube