Memory RAM 1x 8GB Apple iMac Late 2013 DDR3 1600MHz SO-DIMM | E-OWC1600DDR3S8GB | APPLE \ MEMORY FOR APPLE \ OWC \ APPLE IMAC \ iMac Late 2013 \ iMac 21.5''(Late 2013)
Timetec 32GB KIT(4x8GB) Compatible for Apple DDR3L 1600MHz PC3L-12800 CL11 for iMac (Mid 2011, Late 2012, Late 2013, Late 2014 Retina 5K, Mid 2015 Retina 5K) SODIMM Memory Module MAC RAM Upgrade at Amazon.com
Install memory in an iMac - Apple Support
8GB -2x4GB Memory Ram Upgrade for 27" Apple iMac-14.2 Core i7 3.5GHz Late 2013 | eBay
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Apple Posts iMac (Late 2013) Memory Specifications
The Display - 21.5-inch iMac (Late 2013) Review: Iris Pro Driving an Accurate Display
Memory upgrade: Apple iMac 2012/2013/2014 (Howto)
CMS 32GB (4X8GB) Memory Ram Compatible with Apple Imac "Core I5" 3.2 27-Inch (Late 2013) Me088Ll/A - A6 - Newegg.com