32.0GB OWC Memory Upgrade Kit For 2010-2011 Apple iMac
Install memory in an iMac - Apple Support
How to Upgrade iMac RAM (21.5" and 27" Aluminum): EveryMac.com
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Timetec 32GB KIT(4x8GB) Compatible for Apple DDR3L 1600MHz PC3L-12800 CL11 for iMac (Mid 2011, Late 2012, Late 2013, Late 2014 Retina 5K, Mid 2015 Retina 5K) SODIMM Memory Module MAC RAM Upgrade at Amazon.com
install - Installing and Upgrading Ram on a mid 2011 iMac (different size RAM) - Ask Different
Upgrade your iMac's RAM in less than 5 minutes - YouTube