A-Tech 32GB (4x8GB) RAM for Apple iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
iMac 21.5" Mid 2011 How To Change/Upgrade Your Ram For Better Performance 2014 - YouTube
Install memory in an iMac - Apple Support
Apple iMac Mid 2011 21.5-inch 2.7GHz Core i5 Apple DDR3 RAM Memory | Kingston
Review: 21.5-inch 2012 iMac takes two steps forward, one step back | Ars Technica
Memory Upgrades for Apple iMac 2011 Up to 32GB
Memory RAM Upgrade for Apple iMac 21.5-inch Mid 2011 4GB/8GB DDR3 SODIMM | eBay
Maximum memory for 2011 iMac - Ask Different
How to Upgrade iMac RAM (21.5" and 27" Aluminum): EveryMac.com
OWC SSD Upgrade Kits For 21.5-Inch iMac 2011
32.0GB OWC Memory Upgrade Kit For 2010-2011 Apple iMac
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Teardown of new 21.5-inch iMac surprisingly reveals user-upgradable RAM, modular CPU - 9to5Mac
Apple iMac 21.5-inch Mid 2011 2.5GHz Intel Core i5 (MC309LL/A) – UNICOM, Inc.
OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com
Install memory in an iMac - Apple Support
Apple iMac 2011 (Mid) 21.5-inch (iMac 11,2) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre