Amazon.com: Lenovo ThinkPad T520 Laptop Notebook - Intel Core i5 2.5GHz - 8GB DDR3 - 128GB SSD - 15.6in Display- DVD - Windows 10 Pro (Renewed) : Electronics
CMS 16GB (2X8GB) DDR3 10600 1333MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Lenovo® Thinkpad T520 4239; 4240, 4241, 4242, 4243 - A13 at Amazon.com
Arch Memory 4GB 204-Pin DDR3 1333 MHz So-dimm RAM for Lenovo ThinkPad T520 4240-4AU 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