Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
The Display - 21.5-inch iMac (Late 2013) Review: Iris Pro Driving an Accurate Display
Adamanta 4GB (1x4GB) Apple Memory Upgrade for Late 2013 iMac 21.5" and 27" DDR3L 1600Mhz PC3-12800 SODIMM 2Rx8 CL11 1.35v RAM at Amazon.com
How to Upgrade iMac RAM: 2012-2022: EveryMac.com
Install memory in an iMac - Apple Support
New CPUs, faster Wi-Fi, same flaws: Apple's 2013 iMac reviewed | Ars Technica
Apple 21.5" Certified Refurbished iMac Desktop Intel Core i3 3.3GHz 4GB Memory 500GB HDD (2013) Silver ME699LL/A - Best Buy
Upgrading an iMac — Buchanan Consulting
I got a FREE 2013 iMac 21.5 with internal upgrades including Samsung evo ssd and 16gigs of ram. Then used open legacy patcher to install Mac OS Venture 13.5 beta. : r/osx