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
Timetec 16GB KIT(2x8GB) Compatible for Apple Late 2015 iMac (27-inch w/Retina 5K Display)
Install memory in an iMac - Apple Support
CMS 32GB (4X8GB) DDR3 12800 1600MHz Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® iMac Core I7 3.4 27-Inch (Late 2012) - A6 at Amazon.com
Apple iMac 27" - Late 2012 Reviews, Pros and Cons | TechSpot
Apple's 27" iMac Late 2012 model. How to upgrade the ram to 16GB - YouTube
iMac | 3.4 GHz Intel i7 | 27 Inch | Late 2012 - Techable.com
How To Upgrade RAM on the Apple iMac 2012 - 2013 RAM Upgrade - 21.5 inch model - YouTube