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
Install memory in an iMac - Apple Support
Timetec 16GB KIT(2x8GB) Compatible for Apple DDR3L 1600MHz for Mac Book Pro(Early/Late 2011,Mid 2012), iMac(Mid 2011,Late 2012,Early/Late 2013,Late 2014,Mid 2015), Mac Mini(Mid 2011,Late 2012) MAC RAM at Amazon.com
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
Apple iMac (Late 2012) review (21.5- and 27-inch) | Macworld
How to Upgrade iMac RAM: 2012-2022: EveryMac.com
Apple iMac 27" - Late 2012 Reviews, Pros and Cons | TechSpot