Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
The Case of the Late-2012 iMacs - MacStories
Review: 21.5-inch 2012 iMac takes two steps forward, one step back | Ars Technica
16GB -2x8GB Memory Ram Upgrade for 27" Apple iMac-13.2 Core i5 2.9GHz Late 2012 | eBay
How to Upgrade/Install Memory in a 21.5-inch iMac (Late 2012– Mid 2014) iMac14,1 iMac14,3 - YouTube
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
A-Tech 32GB Kit (4x8GB) RAM for Apple iMac (Late 2012, Late 2013, Late 2014, Mid 2015) | DDR3 1600MHz SODIMM PC3-12800 204-Pin SO-DIMM Max Memory Upgrade at Amazon.com
Install memory in an iMac - Apple Support
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013