D. Keltner, P. Ekman, S. Petridis, H. Gunes, S. Kaltwang et al., Facial Expression Of Emotion Handbook of emotions. págs. 236-249 Static vs. dynamic modeling of human nonverbal behavior from multiple cues and modalities, Proceedings of the 2009 international conference on Multimodal interfaces, pp.23-30, 2000.

I. Hupont, E. Cerezo, and S. Baldassarri, Sensing facial emotions in a continuous 2D affective space, 2010 IEEE International Conference on Systems, Man and Cybernetics, p.10, 2010.
DOI : 10.1109/ICSMC.2010.5641717

C. M. Whissell, A Dictionary of Affect in Language: V. What is An Emotion?, Perceptual and Motor Skills, vol.62, issue.3, 1989.
DOI : 10.2466/pms.1986.62.3.875

R. Kalman, A New Approach to Linear Filtering and Prediction Problems. Transactions of the ASME ? Journal of Basic Engineering, pp.35-45, 1960.
DOI : 10.1115/1.3662552

P. Kumar and E. A. Yildirim, Minimum-Volume Enclosing Ellipsoids and Core Sets, Journal of Optimization Theory and Applications, vol.37, issue.12, pp.1-21, 2005.
DOI : 10.1137/1.9781611970791

URL : http://citeseerx.ist.psu.edu/viewdoc/summary?doi=