How to Upgrade Memory in a 21.5-inch or 27-inch iMac (Mid 2010) - YouTube
Install memory in an iMac - Apple Support
iMac RAM for Model 11.2 to 11.3 (i3) | Mid 2010 | RAMJET.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
Apple iMac 2009 (Late) 27-inch 2K (iMac 11,1) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre
Apple iMac 2010 (Mid) 21.5-inch (iMac 11,2) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre