M.  Nardelli, Greco, A., Bianchi, M., Scilingo, E. P., and Valenza, G., ?On the Pleasantness of a Haptic Stimulation: How Different Textures can be Recognized through Heart Rate Variability Nonlinear Analysis?, IEEE Engineering in Medicine and Biology Society (EMBC 2016). Orlando, USA, August 16-20, 2016, 2016.