How to Upgrade MacBook Pro RAM (2009, 2010, 2011, 2012): EveryMac.com
SOLVED: Can RAM be upgraded? - MacBook Pro 13" Retina Display Mid 2014 - iFixit
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MacBook Pro (Retina, 13-inch, Mid 2014) - Technical Specifications
16GB MacBook Pro RAM Upgrade (2011/2012/2013) - YouTube
2.5GHz 16GB RAM Logic Board 820-3787-A for MacBook Pro 15" A1398 Late 2013 2014 | eBay
Apple Macbook Pro 13 Mid-2014 2.8GHz i5, 16GB RAM LOGIC BOARD | eBay
MacBook Pro (Retina, 13-inch, Mid 2014) - Technical Specifications
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
Apple Macbook Pro 13 A1502 Logicboard i5 - 2.8GHz/16GB RAM 820-3476-A 2014 | eBay