Apple's 2012 iMac: Ready for its close-up (pictures) - CNET
Install memory in an iMac - Apple Support
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
Amazon.com: Apple iMac 27-Inch Desktop, 3.4 GHz Intel Core i7 Processor, 16 GB memory, 1TB HDD (Renewed),macOS High Sierra : Electronics
Apple iMac (Late 2012) review (21.5- and 27-inch) | Macworld