CMS 32GB (4X8GB) DDR3 12800 1600MHz Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® iMac Core I5 3.2 27-Inch (Late 2013) Me088Ll/A - A6 at Amazon.com
Memory upgrade: Apple iMac 2012/2013/2014 (Howto)
Apple's new 'Assembled in USA' iMac a bear to upgrade, repair • The Register
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
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
2013 iMac teardowns reveal SSD slots, soldered-in CPU in the 21.5” model | Ars Technica
Install memory in an iMac - Apple Support
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
How to upgrade RAM iMac late 2013 21.5inch - break & fix MOVIE - YouTube