MacBook Pro 13" (Late 2011) 1600MHz Ram - Apple Community
MacBook Pro 13" Unibody Early 2011 RAM Replacement - iFixit Repair Guide
macos - What is the maximum amount of RAM a 2011 MacBook Pro can utilize? - Ask Different
Amazon.com: Timetec 16GB KIT(2x8GB) Compatible for Apple DDR3 1333MHz PC3-10600 CL9 for Mac Book Pro (Early/Late 2011 13/15/17 inch), iMac(Mid 2010, Mid/Late 2011 21.5/27 inch), Mac Mini(Mid 2011) MAC RAM Upgrade :
Memory/ RAM Upgrades For Apple MacBook Pro 2011 from OWC
MacBook Pro 13" Unibody Early 2011 RAM Replacement - iFixit Repair Guide
How to Upgrade MacBook Pro RAM (2009, 2010, 2011, 2012): EveryMac.com
MacBook Pro: How to remove or install memory - Apple Support
Apple 13" MacBook Pro 2011 2.4GHz Core i5 500GB HDD 4GB A1278 MD313LL/A +C Grade 885909531653 | eBay
How To: MacBook Pro Late 2011 Memory Upgrade - 16GB (2 X 8GB) : 6 Steps - Instructables
How To: MacBook Pro Late 2011 Memory Upgrade - 16GB (2 X 8GB) : 6 Steps - Instructables
Apple Adds Early 2011 13-Inch MacBook Pro to Obsolete Products List - MacRumors