8GB -2x4GB Memory Ram Upgrade for 27" Apple iMac-14.2 Core i7 3.5GHz Late 2013 | eBay
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
Apple iMac 21.5-inch and 27-inch (Late 2013) reviews | Macworld
iMac RAM Upgrade mixing different memory sticks: 27” iMac late 2013 - YouTube
Install memory in an iMac - Apple Support
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
SSD Upgrades for Apple iMac 27-Inch Late 2013 - 2019
How to UPGRADE RAM in the (Mid 2017) 5K iMac & save $$$! - YouTube
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
How to upgrade RAM iMac late 2013 21.5inch - break & fix MOVIE - YouTube
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
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