Schalk G, McFarland DJ, Hinterberger T, Birbaumer N, Wolpaw J. BCI2000: a general-purpose brain-computer interface (BCI) system. IEEE Trans Biomed Eng. 2004;51(6):1034-43. 

Leuthardt EC, Schalk G, Wolpaw J, Ojemann JG, Moran D. A brain-computer interface using electrocorticographic signals in humans. J Neural Eng [Internet]. 2004;1(2):63-71. http://www.ncbi.nlm.nih.gov/pubmed/15876624