Apple's 27" iMac Late 2012 model. How to upgrade the ram to 16GB - YouTube
Amazon.com: Apple iMac MNE92LL/A 27 Inch, 3.4 GHz Intel Core i5, 8GB RAM, 1TB Fusion Drive, Silver (Renewed), Mac OS : Electronics
Timetec 16GB KIT(2x8GB) Compatible for Apple Late 2015 iMac (27-inch w/Retina 5K Display)
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
A-Tech 8GB Kit (2x4GB) 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
A-Tech 32GB Kit (4x8GB) RAM for Apple iMac (Late 2012, Late 2013, Late 2014, Mid 2015) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
The Case of the Late-2012 iMacs - MacStories
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Apple's 2012 iMac: Ready for its close-up (pictures) - CNET
Apple iMac 27" - Late 2012 Reviews, Pros and Cons | TechSpot
iMac (27-inch, Late 2012) - Technical Specifications