iMac | 2.26 GHz Core 2 Duo | 20 Inch | Mid 2009 - Techable.com
Memory Upgrades for Apple iMac 2009 - Up to 32GB
How to Upgrade Memory in a Late 2009 21.5-inch or 27-inch iMac - YouTube
Timetec 8GB KIT(2x4GB) Compatible for Apple DDR3 1067MHz / 1066MHz PC3-8500 CL7 for Mac Book,
Install memory in an iMac - Apple Support
iMac (2009) RAM & Storage Upgrades
Install memory in an iMac - Apple Support
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Install memory in an iMac - Apple Support
Timetec 8GB KIT(2x4GB) Compatible for Apple DDR3 1067MHz / 1066MHz PC3-8500 CL7 for Mac Book, Mac Book Pro, iMac, Mac Mini (Late 2008, Early/Mid/Late 2009, Mid 2010) SODIMM Memory MAC RAM Upgrade