How to Upgrade iMac RAM (21.5" and 27" Aluminum): EveryMac.com
Repair iMac 27 inch Late 2009 - iFixRapid
Install memory in an iMac - Apple Support
iMac Repair & Upgrade, Same Day Services
iMac Intel 27" Sustitución RAM EMC 2309 y 2374 - Guía de reparación iFixit
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
Apple iMac (27-inch, Late 2009) Serial Number Lookup - AppleSN.info
How to Upgrade iMac Hard Drive (2009, 2010, 2011): EveryMac.com
Apple iMac Upgrades | SimplyFixIt
A1312 Power Supply (310W) for Apple iMac 27 inch A1312 (EMC 2309) (EMC 2374), ( Late 2009- Mid 2011) - MacWave
Memory Upgrades for Apple iMac 2009 - Up to 32GB
Install memory in an iMac - Apple Support
27" iMac Late 2009 A1312 Disassembly RAM SSD Hard Drive Upgrade LCD Screen Glass Replacement Repair - YouTube
A-Tech 32GB (4 x 8GB) PC3-8500 DDR3 1066/1067 MHz RAM for iMac Late 2009 27- inch (Quad-Core i5/i7) | 204-Pin SODIMM Max Memory Upgrade Kit at Amazon.com