Busch V, Zeman F, Heckel A, Menne F, Ellrich J, Eichhammer P. The effect of transcutaneous vagus nerve stimulation on pain perception ? An experimental study. Brain Stimulation [Internet]. 2013;6(2):202 - 209. http://linkinghub.elsevier.com/retrieve/pii/S1935861X12000708