Amazon.com: Timetec 16GB KIT(2x8GB) Compatible for Apple DDR3 1333MHz PC3-10600 CL9 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) MAC RAM Upgrade :
How to Upgrade Memory in a 21.5-inch or 27-inch iMac (Mid 2010) - YouTube
iMac RAM for Model 11.2 to 12.2 | DDR3-1066MHz | 4GBx4 | MacMemory.com
16GB 2X 8GB DDR3 RAM MEMORY FOR APPLE IMAC MODEL# IMAC11,2 IMAC11,3 A1311 A1312 | eBay
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
iMac RAM Upgrade - Apple iMac/iMac Pro Memory - NEMIX RAM™ - Page 7
Best Buy: Apple® iMac® / Intel® Core™ i3 Processor / 27" Display / 4GB Memory / 1TB Hard Drive MC510LL/A
CMS 16GB (4X4GB) DDR3 10600 1333MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® iMac Core I3 3.06 21.5-Inch (Mid-2010) - A28 at Amazon.com
8GB [2x4GB] DDR3-1333 RAM Memory Upgrade Kit for The Apple iMac 11,2 (21.5-inch, 3.2GHz, MC509LL/A) Intel Core i3 (Genuine A-Tech Brand) at Amazon.com