From Amazon
Corsair Value Select SODIMM 4GB (1x4GB) DDR3 1333MHz C9 Memory for Laptop/Notebooks - Black
Conrad Electronic
Corsair Value Select Laptop RAM card DDR3 4 GB 1 x 4 GB 1333 MHz 204-pin SO-DIMM CL9 9-9-24 CMSO4GX3M1A1333C9
OnBuy
Corsair CMSO4GX3M1A1333C9 RAM Module - 4 GB (1 x 4 GB) - DDR3-1333/PC3