Timetec 80GB KIT(10x8GB) Compatible for Apple DDR3L 1600MHz PC3L-12800 CL11 for iMac (Mid 2011, Late 2012, Late 2013, Late 2014 Retina 5K, Mid 2015 Retina 5K) SODIMM Memory Module MAC RAM Upgrade - Newegg.com
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
21.5" iMac Has No User-Upgradable RAM; 27" Has Four Accessible RAM Slots - MacRumors
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
Apple iMac (Late 2012) review (21.5- and 27-inch) | Macworld
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
Apple's 2012 iMac: Ready for its close-up (pictures) - CNET
2012 - 21.5" iMac, 2.9GHz Quad Core i5 Processor, 8GB RAM, 250GB SSD, – The Apple Xchange - Preowned Apple Products and Services