HD] Installing RAM on a Lenovo Thinkpad T420 Guide T410 T400 - YouTube
Upgrading Ram from 4Gb to 6Gb on Lenovo Thinkpad T420 - YouTube
Arch Memory 4GB 204-Pin DDR3 1333 MHz So-dimm RAM for Lenovo ThinkPad T420 4177-Q5U at Amazon.com
8GB Stick for IBM Lenovo ThinkPad T Series T420 T420i T420s T520 T520i. SO-DIMM DDR3 Non-ECC PC3-10600 1333MHz RAM Memory. Genuine A-Tech Brand. at Amazon.com