K. O. Akputu, K. P. Seng, and Y. L. Lee, Facial Emotion Recognition for Intelligent Tutoring Environment, 2nd International Conference on Machine Learning and Computer Science (IMLCS'2013), pp.9-13, 2013.

S. Arca, P. Campadelli, and R. Lanzarotti, An automatic feature-based face recognition system, Proceedings of the 5th International Workshop on Image Analysis for Multimedia Interactive Services, 2004.

D. M. Aung and N. Aye, A Facial Expression Classification using Histogram Based Method, International conference on Signal Processing Systems, 2012.

P. Ekman, Basic emotions. Handbook of cognition and emotion, pp.45-60, 1999.

D. Filko and M. Goran, Emotion Recognition System by a Neural Network Based Facial Expression Analysis, Automatika ??? Journal for Control, Measurement, Electronics, Computing and Communications, vol.54, issue.2, pp.263-272, 2013.
DOI : 10.7305/automatika.54-2.73

A. Koutlas and D. I. Fotiadis, An automatic region based methodology for facial expression recognition, 2008 IEEE International Conference on Systems, Man and Cybernetics, pp.662-666, 2008.
DOI : 10.1109/ICSMC.2008.4811353

M. J. Lyons, S. Akamatsu, M. Kamachi, and J. Gyoba, Coding facial expressions with Gabor wavelets, Proceedings Third IEEE International Conference on Automatic Face and Gesture Recognition, pp.200-205, 1998.
DOI : 10.1109/AFGR.1998.670949

A. Mehrabian, Communication without words, Psychology Today, vol.2, issue.4, pp.53-56, 1968.

G. R. Murthy and R. S. Jadon, Recognizing Facial Expressions Using Eigenspaces, International Conference on Computational Intelligence and Multimedia Applications (ICCIMA 2007), pp.201-207, 2007.
DOI : 10.1109/ICCIMA.2007.353

A. Ortony, G. Clore, and A. Collins, The Cognitive Structure of Emotions, 1988.
DOI : 10.1017/CBO9780511571299

M. Pantic and L. J. Rothkrantz, Automatic analysis of facial expressions: The state of the art. Pattern Analysis and Machine Intelligence, IEEE Transactions on, issue.12, pp.22-1424, 2000.

J. P?inosil, Z. Smékal, and A. Esposito, Combining Features for Recognizing Emotional Facial Expressions in Static Images, Verbal and Nonverbal Features of Human-Human and Human- Machine Interaction, pp.56-69, 2008.
DOI : 10.1145/954339.954342

L. Shen, M. Wang, and R. Shen, Affective e -learning: Using " emotional " data to improve learning in pervasive learning environment, In: Educational Technology & Society, vol.12, issue.2, pp.176-189, 2009.

Y. Shinohara and N. Otsu, Facial expression recognition using fisher weight maps, Sixth IEEE International Conference on Automatic Face and Gesture Recognition, 2004. Proceedings., pp.499-504, 2004.
DOI : 10.1109/AFGR.2004.1301582

L. H. Thai, N. D. Nguyen, and T. S. Hai, A facial expression classification system integrating canny, principal component analysis and artificial neural network. arXiv preprint, 2011.

Y. Tian, T. Kanade, and J. F. Cohn, Facial Expression Recognition, Handbook of face recognition, pp.487-519, 2011.
DOI : 10.1007/978-0-85729-932-1_19

A. Verma and L. K. Sharma, A Comprehensive Survey on Human Facial Expression Detection, International Journal of Image Processing (IJIP), vol.7, issue.2, p.171, 2013.