How to Upgrade MacBook RAM (13-Inch Aluminum Unibody): EveryMac.com
A-Tech 4GB PC3-8500 DDR3 1066/1067 MHz RAM for MacBook, MacBook Pro, iMac, Mac Mini (Late 2008, Early/Mid/Late 2009, Mid 2010) | 204-Pin SODIMM Memory Upgrade Module at Amazon.com
RAM upgrade and/or SSD drive – what's the benefit?
MacBook Air 2008: 10th anniversary review flashback - CNET
13-inch MacBook Late 2008 Memory Installation Video - YouTube
MacBook Pro Memory Upgrade Kits (2008, 2009 and 2010)
A-Tech 8GB RAM for Apple MacBook Pro (Mid 2012), iMac (Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini (Late 2012) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
Apple MacBook Air A1237 13.3" Laptop (January, 2008) - Customized for sale online | eBay
MacBook Pro Memory Upgrade Kits (2008, 2009 and 2010)
RAM Upgrades For Apple MacBook (2009 - 2010) from OWC