Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
Memory upgrade: Apple iMac 2012/2013/2014 (Howto)
Install memory in an iMac - Apple Support
Apple's 2012 iMac: Ready for its close-up (pictures) - CNET
iMac Intel 21.5" EMC 2544 Teardown - iFixit
NEMIX RAM 16GB Kit (2x8GB Upgrade) DDR3-1600 SODIMM PC3-12800 for Apple MacBook Pro Mid 2012 / iMac Late 2012 / iMac 2013, Late 2014, Mid 2015, Mac Mini Late 2012 at Amazon.com
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
CMS 16GB (2X8GB) DDR3 12800 1600MHz Non ECC SODIMM Memory Ram Upgrade Compatible with Apple®
Apple iMac 2012 (Late) 21.5-inch (iMac 13,1) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre