A1398 Logicboard, 820-3787-A, 661-8303 Logic Board for Apple MacBook Pro Retina 15-inch A1398 Late 2013, Mid 2014 (Dual Graphics-DG) Core i7 2.5Ghz 16GB RAM, EMC #: 2674, 2876 - WIT Computers
Apple MacBook Pro (15-inch, 2013) review: Apple's high-end laptop gets better battery life and a lower price - CNET
A-Tech 8GB Kit (2x4GB) 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 Pro 15.4" (512GB SSD, Intel Core i7-4960HQ, 2.60GHz, 16GB RAM) Laptop - Silver - ME874LL/A for sale online | eBay
How to Upgrade RAM on MacBook Pro, iMac & More | AVG