1GB Black Diamond Memory Module for IBM ThinkPad R Series R52 (Type 1847) DDR2 SO-DIMM 200pin PC2-4200 533MHz Upgrade System Specific Memory - Newegg.com
CMS 2GB (2X1GB) DDR2 4200 533MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with IBM Lenovo® Thinkpad R52, 73P3845 Notebook Series Ddr2 - A59 at Amazon.com
IBM R52 Thinkpad: How to Remove and Upgrade RAM Memory Module - YouTube