iMac Intel 21.5" Retina 4K Display (2017) RAM and SATA Hard Drive Upgrade - iFixit Repair Guide
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
Apple iMac (27-inch, 2017) review: Apple doesn't mess with success - CNET
HOW TO UPGRADE NEW 2017 IMAC RAM - YouTube
Memory Upgrades for 2017 iMac 27-Inch
Amazon.com: OWC 32GB (2 x 16GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S32P) : Everything Else
OWC Performance Upgrades for iMac 2010
Teardown of New 4K 21.5-inch iMac Reveals Removable RAM and Modular CPU - MacRumors