16GB -2x8GB Memory Ram Upgrade 21.5" Apple iMac-13.1 Core i5 2.7GHz Late 2012 | eBay
The New 2017 iMac: Notes & Tidbits on RAM - The Mac Observer
Timetec 16GB KIT(4x4GB) Compatible for Apple DDR3 1067MHz / 1066MHz PC3-8500 CL7 Dual Rank for iMac (Late 2009 21.5-inch / 27-inch) SODIMM Memory MAC RAM Upgrade for iMac 10,1 and iMac 11,1 at Amazon.com
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013