Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
How to Upgrade/Install Memory in a 21.5-inch iMac (Late 2012– Mid 2014) iMac14,1 iMac14,3 - YouTube
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
A-Tech 32GB Kit (4x8GB) RAM for Apple iMac (Late 2012, Late 2013, Late 2014, Mid 2015) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com
iMac 14,1 (21.5-inch, Late 2013)
16GB -2x8GB Memory Ram Upgrade 21.5" Apple iMac-14.1 Core i5 2.7GHz Late 2013 | eBay