How to Upgrade MacBook Pro RAM (2009, 2010, 2011, 2012): EveryMac.com
MacBook Pro 15" Retina Display Mid 2012 Teardown - iFixit
Mid-2012 Macbook Pro 16GB RAM Upgrade How To - YouTube
16GB MacBook Pro RAM Upgrade (2011/2012/2013) - YouTube
How to upgrade your 2011 or 2012 Macbook Pro RAM (with Step-by-Step photos) – Amanda Xi
Samsung ram Memory Upgrade DDR3 PC3 12800, 1600MHz, 204 PIN, SODIMM for 2012 Apple MacBook Pro's, 2012 iMac's, and 2011/2012 Mac Mini's (16GB kit (2 x 8GB)) at Amazon.com