Apple iMac 2012 (Late) 21.5-inch (iMac 13,1) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre
What Does It Take To Upgrade a 2012 iMac 21.5"?
New 21.5-inch iMac least repairable yet due to lack of RAM, hard drive upgradability - 9to5Mac
Apple iMac Late 2012 21.5-inch 2.7 GHz Core i5 Desktop DDR3 RAM Memory | Kingston
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
Timetec Hynix IC Apple 8GB DDR3L 1600MHz PC3L-12800 SODIMM Memory upgrade For MacBook Pro 13-inch/15-inch Mid 2012, iMac 21.5-inch Late 2012/ Early/ Late 2013 (8GB) - Walmart.com
Install memory in an iMac - Apple Support
New iMac 21" Review: Thin, Immersive Display Stands Out (Part 1)