Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
27" iMac Offers Easier RAM Upgrade
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
How To Upgrade RAM on the Apple iMac 2012 - 2013 RAM Upgrade - 21.5 inch model - YouTube
Apple iMac 27" - Late 2012 Reviews, Pros and Cons | TechSpot
Timetec 16GB KIT(2x8GB) Compatible for Apple Late 2015 iMac (27-inch w/Retina 5K Display)
iMac | 3.4 GHz Intel i7 | 27 Inch | Late 2012 - Techable.com