Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
A-Tech 8GB RAM for Apple MacBook Pro (Mid 2012), iMac (Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini (Late 2012) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
iMac Intel 21.5" EMC 2638 Teardown - iFixit
iMac 2013 Model Ram Upgrade - YouTube
16GB -2x8GB Memory Ram Upgrade 21.5" Apple iMac-14.1 Core i5 2.7GHz Late 2013 | eBay
Apple iMac 21.5" Late 2013 A1418 Logic Board i5 2.9GHz 5200 1GB 1GB 66 | MacKing