MacBook Pro 15" Retina Display Late 2013 Teardown - iFixit
MacBook Pro 15" Retina Display Mid 2012 Teardown - iFixit
Odyson - Logic Board 2.3GHz i7, 16GB Replacement for MacBook Pro 15" Retina A1398 (Mid 2012, Early 2013)
Upgrading RAM in Your MacBook Pro 13" or 15" : 19 Steps (with Pictures) - Instructables
Amazon.com: Apple MacBook Pro 15" Retina Core i7 2.6GHz MLH32LL/A with Touch Bar, 16GB Memory, 512GB Solid State Drive Space Gray(Renewed) : Electronics
Amazon.com: Apple MacBook Pro 15 inches Laptop Intel Quad Core i7 2.8GHz (MD831_BTO) Retina Display, 16GB Memory, 768GB Solid State Drive (Renewed) : Electronics