Review: 21.5-inch 2012 iMac takes two steps forward, one step back | Ars Technica
8GB Memory (PC3L-12800, DDR3L 1600MHz) for Apple MacBook Pro 15 inch A1286 Mid 2012. Apple MacBook Pro 13 inch A1278 - Mid 2012. iMac 21.5 inch A1418 Late 2012, A1418 Early 2013,
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
Review: Apple iMac 21.5in late 2012 • The Register
Install memory in an iMac - Apple Support
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET