A-Tech 8GB RAM for Apple MacBook Pro (Mid 2012), iMac (Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini (Late 2012) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
MacBook Pro (Retina, 15-inch, Mid 2012) - Technical Specifications
MacBook Pro 15" Unibody Mid 2012 Teardown - iFixit
Memory RAM Upgrades for MacBook Pro (2012 - Late 2016)
MacBook Pro with Retina display review (13-inch, 2015) | Engadget
MacBook Pro 15" (2012) - QWERTY - English Retina - Core i7 - 2.3 GHz - SSD 256 GB - RAM 16GB | Back Market