MacBook Pro: How to remove or install memory - Apple Support
Apple MacBook Pro Mid-2009 15" Laptop | 2.53GHz | 4GB | 250GB | MacOSX – Dynamic Computer Surplus
OWC 6GB (2GB + 4GB) PC8500 DDR3 1066MHz SO-DIMMs Memory Compatible with Late 2008, Early 2009, Early 2010 MacBook, MacBook Pro Unibody Models, 2009/2010 Mac Mini, 2009 iMac Models at Amazon.com