Upgrading RAM in Your MacBook Pro 13" or 15" : 19 Steps (with Pictures) - Instructables
Add more RAM to your MacBook Pro (photos) - CNET
Macbook Pro Ram Upgrade - YouTube
Is there a way to upgrade the RAM in an early 2015 MacBook Pro without voiding the warranty? - Quora
MacBook Unibody Model A1278 RAM Replacement - iFixit Repair Guide
Adamanta 16GB (2x8GB) Apple Memory Upgrade DDR3L 1600MHz SODIMM Compatible for iMac (Mid 2011, Late 2012, Early/Late 2013, Late 2014, Mid 2015), MacBook Pro (Early/Late 2011, Mid 2012), Mac Mini at Amazon.com
MacBook Pro: How to remove or install memory - Apple Support
How to Upgrade MacBook Pro RAM (2009, 2010, 2011, 2012): EveryMac.com
8GB RAM Upgrade for 2011 MacBook Pro & Mac Mini Core i5 & i7 – $34 | OSXDaily