parts-quick 4GB Memory for Apple iMac 27-inch (Late 2013) 1600MHz DDR3 SO-DIMM RAM Brand at Amazon.com
Buy 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
Install memory in an iMac - Apple Support
OWC Memory Upgrade Kits for Apple iMac Pro 2017
Apple Memory Module 16GB DDR4 2400MHz SO-DIMM (2x8GB) - Apple
2017 21.5-inch 4K iMac memory upgrade kit includes 32GB of RAM, tools to take it apart | AppleInsider
Memory upgrade: Apple iMac 2012/2013/2014 (Howto)
How to replace the RAM in the 27-inch iMac | iMore
How to Install RAM in an iMac: 5 Steps (with Pictures) - wikiHow