Samsung original 4GB, 204-pin SODIMM, DDR3 PC3L-12800, ram memory module for laptop ( M471B5173QH0-YK0 ) at Amazon.com
OWC 8GB PC3-12800 DDR3L 1600MHz SO-DIMM 204 Pin CL11 Memory Module Upgrade Compatible with iMac, Mac Mini, and MacBook Pro (OWC1600DDR3S8GB) at Amazon .com
Crucial 8GB Single DDR3/DDR3L 1866 MT/s (PC3-14900) Unbuffered SODIMM 204-Pin Memory - CT102464BF186D at Amazon.com
Amazon.com: 8GB 2 X 4GB DDR3 PC3-8500 1066MHz SODIMM Memory RAM for Apple iMac Intel Core 2 Duo 20" inch 24" inch (Early 2009) Equivalent to MC016G/A (PARTS-QUICK BRAND) : Electronics