New 16GB 4x4GB Memory Apple iMac (21.5 and 27-inch, Mid 2011) PC3-10600 at Amazon.com
NEMIX RAM 32GB (4x8GB Upgrade) DDR3-1333 PC3-10600 204-Pin SODIMM Memory for Apple MacBook Pro Early/Late 2011, iMac Mid 2010 27 inch 4-Core, iMac Mid 2011 21.5/27”, Mac Mini Mid 2011 at Amazon.com
Install memory in an iMac - Apple Support
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 memory in an iMac - Apple Support
32GB (4 x 8GB) 1333MHz DDR3 SO-DIMM PC3-10600 204Pin SO-DIMM CL9 Memory RAM Upgrade Module Compatible with Mid 2010/2011 21.5" & 27" iMac Models (OWC1333DDR3S32S) at Amazon.com
How to Upgrade Memory in a 21.5-inch or 27-inch iMac (Mid 2010) - YouTube
16GB -2x8GB Memory Ram Upgrade for 27" Apple iMac-12.2 Core i7 3.4GHz Mid 2011 | eBay
Amazon.com: Timetec 8GB KIT(2x4GB) Compatible for Apple DDR3 1333MHz PC3-10600 for Mac Book Pro (Early/Late 2011 13/15/17 inch), iMac (Mid 2010, Mid/Late 2011 21.5/27 inch), Mac Mini(Mid 2011) RAM Upgrade : Electronics
Maximum memory for 2011 iMac - Ask Different
Install memory in an iMac - Apple Support (MT)
Memory Upgrades for Apple iMac 2011 Up to 32GB
32.0GB OWC Memory Upgrade Kit For 2010-2011 Apple iMac
How to Upgrade iMac RAM (21.5" and 27" Aluminum): EveryMac.com
Install SSD iMac 2011 - How-To DIY Guide Tutorial
How do you install RAM in your iMac? - Coolblue - anything for a smile
Install memory in an iMac - Apple Support
Memory RAM Upgrade for Apple iMac 21.5-inch Mid 2011 4GB/8GB DDR3 SODIMM | eBay