Apple's 2012 iMac: Ready for its close-up (pictures) - CNET
upgrade advice for a late 2013 27-inch iMac | MacRumors Forums
iMac 27" 3.2GHz (Late 2013) | mac of all trades
Install memory in an iMac - Apple Support
Differences Between Late 2012 and Late 2013 Aluminum iMac: EveryMac.com
21.5" iMac Has No User-Upgradable RAM; 27" Has Four Accessible RAM Slots - MacRumors
Mac RAM Upgrade, Best iMac Memory Upgrade – Best Reviews
iMac 27-inch (2013) Review | Trusted Reviews
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