16GB MacBook Pro RAM Upgrade (2011/2012/2013) - YouTube
MacBook Pro: How to remove or install memory - Apple Support
Teardown of Retina MacBook Pro finds soldered RAM, proprietary SSD | AppleInsider
A-Tech 16GB Kit (2x8GB) 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
How to upgrade the RAM of a MacBook Pro to 16GB - Quora