iMac with Retina 5K Display 2014/2015 Memory Upgrades
16GB -2x8GB Memory Ram Upgrade for 27" Apple iMac-15.1 Core i7 4.0GHz Late 2014 | eBay
Install memory in an iMac - Apple Support
Memory in New $1099 iMac is Soldered and Not Upgradable - MacRumors
How to Upgrade iMac RAM: 2012-2020: EveryMac.com
Install memory in an iMac - Apple Support
Adamanta 16GB (2x8GB) Compatible for MacBook Pro (Early/Late 2011, Mid 2012), iMac (Mid 2011, Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini DDR3L 1600MHz SODIMM Memory Upgrade at Amazon.com
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET