iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Memory Upgrades for Apple iMac 2011 Up to 32GB
How to Upgrade iMac RAM (21.5" and 27" Aluminum): EveryMac.com
iMac 27-Inch "Core i7" 3.5 Late 2013 Max RAM is higher than 32gb | MacRumors Forums
How To Upgrade RAM in a Mac | Macworld
A-Tech 8GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com
Upgrade your iMac's RAM in less than 5 minutes - YouTube
Apple iMac 27" i5 2.7 (Mid 2011) - Technical data and benchmarks
Best Buy: Apple 27" iMac All-in-One Computer 8 GB Memory 1 TB Hard Drive ME089LL/A