Han, C.-H.; Hwang, H.-J.; Im, C.-H.: 'Classification of visual stimuli with different spatial patterns for single-frequency, multi-class SSVEP BCI', Electronics Letters, 2013, 49, (22), p. 1374-1376, DOI: 10.1049/el.2013.2792 IET Digital Library, https://digital-library.theiet.org/;jsessionid=qgne7vj93s55.x-iet-live-01content/journals/10.1049/el.2013.2792