Samsung original 4GB, 204-pin SODIMM, DDR3 PC3L-12800, ram memory module for laptop ( M471B5173QH0-YK0 ) at Amazon.com
Vaseky Knight Game Memory Ram DDR3 16GB(2*8GB)Kit Support Dual Channel 1600MHz Chips Unbuffered DIMM DDR3 PC3 12800 for Intel AMD System Desktop Memory Model with Cooling Vest Desktop Memory - Newegg.com
8GB Kingston Value Ram DDR3 1600MHz PC3-12800 CL11 1.5V Dual Memory Kit (2 x 4GB)