21.5-inch iMac (Late 2013) Review: Iris Pro Driving an Accurate Display
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
Late 2013 iMac review: Faster than before, but the gains over previous models are modest | Macworld
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
16GB -2x8GB Memory Ram Upgrade 21.5" Apple iMac-14.1 Core i5 2.7GHz Late 2013 | eBay
How to upgrade RAM iMac late 2013 21.5inch - break & fix MOVIE - YouTube