Refurbished: Lenovo ThinkPad T520 15.6" Notebook with Intel Core i5-2520M 2.50Ghz, 4GB RAM, 320GB HDD, DVDRW, Webcam, Windows 10 Professional 64 Bit - Newegg.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
for Lenovo Thinkpad T520 W700 W710 W510 T510 T420 Notebook 8X DL DVD RW RAM Double Layer Burner 24X CD Recorder Optical Drive|optical drive|dvd rwcd recorder - AliExpress
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