Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
How to Upgrade RAM in a 27" iMac (2012) - YouTube
Install memory in an iMac - Apple Support
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
iMac RAM for Model 13.2 to 15.1| DDR3-1600MHz | 8GBx4 | MacMemory.com
How to Upgrade iMac RAM: 2012-2022: EveryMac.com
IMAC 21.5" LATE 2012 I5 8GB RAM 1 TB HDD GEFORCE GT 640M MOUNTAIN LION OS T4-C7 | eBay
The Case of the Late-2012 iMacs - MacStories
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