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
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
How to Upgrade/Install Memory in a 21.5-inch iMac (Late 2012– Mid 2014) iMac14,1 iMac14,3 - YouTube
Upgrade RAM on Apple Retina iMac 5K (Late 2015) / How To install memory - YouTube
Apple iMac 2013 (Late) 21.5-inch (iMac 14,3) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre
Apple Classifies Early 2013 21.5-inch iMac as Obsolete - MacRumors
Apple iMac 21.5-inch and 27-inch (Late 2013) reviews | Macworld
Install memory in an iMac - Apple Support
How to Upgrade Memory in a 27-inch iMac (Late 2012-2013) iMac13,2 and iMac14,2 - YouTube
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET