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 RAM / Memory on a 2010 iMac Core i3 i5 i7 (21.5in & 27in) - YouTube
Install memory in an iMac - Apple Support
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
Mac Mini Memory for Model 4.1 | DDR3 1066MHz | 2010 | Ramjet.com
Install memory in an iMac - Apple Support
How I kept my iMac running for a decade | Cult of Mac
How to Upgrade the RAM in Your iMac
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
32.0GB OWC Memory Upgrade Kit For 2010-2011 Apple iMac
A-Tech 4GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010, Mid 2011, Late 2011), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com