Timetec 32GB KIT(4x8GB) 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 at Amazon.com
Apple iMac 2012 (Late) 21.5-inch (iMac 13,1) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre
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
2012 21.5-Inch Apple iMac Review: Slim, Sleek, And Stylish, But Far From Shallow | TechCrunch
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
iMac (27-inch, Late 2012) - Technical Specifications