Source: https://www.researchgate.net/profile/Hubert-Konik/publication/281049612_Une_methode_de_reconnaissance_des_expressions_du_visage_basee_sur_la_perception/links/56027adc08aeaf867fb6b443/Une-methode-de-reconnaissance-des-expressions-du-visage-basee-sur-la-perception.pdf