Amazon.com: Timetec 16GB KIT(2x8GB) Compatible for Apple DDR3L 1600MHz for Mac Book Pro(Early/Late 2011,Mid 2012), iMac(Mid 2011,Late 2012,Early/Late 2013,Late 2014,Mid 2015), Mac Mini(Mid 2011,Late 2012) MAC RAM : Electronics
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
How to upgrade RAM in the (Mid 2017) 5K iMac and save up to ~$900 [Video] - 9to5Mac
install - Installing and Upgrading Ram on a mid 2011 iMac (different size RAM) - Ask Different