iMac 21.5" Mid 2011 How To Change/Upgrade Your Ram For Better Performance 2014 - YouTube
How to Upgrade Memory in a 21.5-inch or 27-inch iMac (Mid 2010) - YouTube
Amazon.com: Timetec 16GB KIT(2x8GB) Compatible for Apple DDR3L 1600MHz for Mac Book Pro(Early/Late 2011,Mid 2012), iMac(Mid 2011,Late 2012,Early/Late 2013,Late 2014,Mid 2015), Mac Mini(Mid 2011,Late 2012) MAC RAM : Electronics
16GB 4GB DDR3 SODIMM 1333MHz Memory Kit For Apple iMac 2011 12.1 12.2 Memory IT | eBay
32.0GB OWC Memory Upgrade Kit For 2010-2011 Apple iMac
A-Tech 8GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com
iMac Mid 2011 (21.5 – inch and 27 – inch) RAM Upgrade Dallas – Apple Mac Computer Repair Dallas , Laptop ,Desktop ,iMac ,MacBook iPhone iPad Data Recovery ,Virus
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Maximum memory for 2011 iMac - Ask Different
iMac 21.5-inch Mid 2011 20G RAM and RAM Access Cover (Crucial and Elpida) | eBay