iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Shop Imac 2013 Memory Upgrade | UP TO 56% OFF
How to upgrade the 27-inch 5K iMac (2019) with a massive 128GB of RAM [Video] - 9to5Mac
Install memory in an iMac - Apple Support
Memory upgrade: Apple iMac 2012/2013/2014 (Howto)
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