@inbook{GrosseWentrupSBG2013, title = {A Review of Performance Variations in SMR-Based Brain–Computer Interfaces (BCIs)}, author = {Grosse-Wentrup, M. and Sch{\"o}lkopf, B.}, booktitle = {Brain-Computer Interface Research}, pages = {39-51}, chapter = {4}, series = {SpringerBriefs in Electrical and Computer Engineering}, editors = {Guger, C., Allison, B. Z. and Edlinger, G.}, publisher = {Springer}, year = {2013}, doi = {10.1007/978-3-642-36083-1_5} }