Apple iMac 2011 (Mid) 21.5-inch (iMac 11,2) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre
Install memory in an iMac - Apple Support
Apple iMac 21.5-inch Mid 2011 2.5GHz Intel Core i5 (MC309LL/A) – UNICOM, Inc.
OWC SSD Upgrade Kits For 21.5-Inch iMac 2011
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
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
Apple iMac review (mid 2011) - The Verge
Install memory in an iMac - Apple Support
A-Tech 16GB (4x4GB) RAM for Apple iMac (Mid 2010, Mid 2011, Late 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
iMac 21,5 2009-2011 LGA 1156 with i7, works good!! | MacRumors Forums
iMac 21.5" Mid 2011 How To Change/Upgrade Your Ram For Better Performance 2014 - YouTube
Apple 21.5" iMac® Intel Core i5 (2.3GHz) 8GB Memory 1TB Hard Drive Silver MMQA2LL/A - Best Buy