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 RAM upgrade: Here's an affordable way to improve multitasking - CNET
How to Upgrade Memory in a 27-inch iMac (Late 2012-2013) iMac13,2 and iMac14,2 - YouTube