Teardown of New 21.5-inch iMac Reveals Glued Down LCD and Dual Microphones - MacRumors
A-Tech 8GB Kit (2x4GB) RAM for Apple MacBook Pro (Mid 2012), iMac (Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini (Late 2012) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
2012 21.5-Inch Apple iMac Review: Slim, Sleek, And Stylish, But Far From Shallow | TechCrunch
Opened up 2012 21.5 iMac for SSD upgrade. | MacRumors Forums
Install memory in an iMac - Apple Support
A-Tech 8GB RAM for Apple MacBook Pro (Mid 2012), iMac (Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini (Late 2012) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com