How to upgrade the 27-inch 5K iMac (2019) with a massive 128GB of RAM [Video] - 9to5Mac
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
iMac 2013 Model Ram Upgrade - YouTube
21.5 inch late 2013 iMac - RAM upgrade - Apple Community
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Apple Classifies Early 2013 21.5-inch iMac as Obsolete - MacRumors
How to UPGRADE RAM in the (Mid 2017) 5K iMac & save $$$! - YouTube
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
Late 2013 iMac review: Faster than before, but the gains over previous models are modest | Macworld