Apple iMac 27" - Late 2009 Reviews, Pros and Cons | TechSpot
Install memory in an iMac - Apple Support
Timetec 16GB KIT(4x4GB) Compatible for Apple DDR3 1067MHz / 1066MHz PC3-8500 CL7 Dual Rank for iMac (Late 2009 21.5-inch / 27-inch) SODIMM Memory MAC RAM Upgrade for iMac 10,1 and iMac 11,1 at Amazon.com
how to upgrade iMac early 2009 SSD and RAM - full class - YouTube
How to Upgrade Memory in a Late 2009 21.5-inch or 27-inch iMac - YouTube