J. Freitas et al.,  "Assessing the applicability of surface EMG to tongue gesture detection", in Advances in Speech and Language Technologies for Iberian Languages, Juan Luis Navarro Mesa; Alfonso Ortega; António Teixeira; Eduardo Hernández Pérez; Pedro Quintana Morales; Antonio Ravelo García; Iván Guerra Moreno; Doroteo T. Toledano, Ed., Switzerland, Springer International Publishing, 2014, vol. 8854, pp. 189-198