FER in primary school children for affective robot tutors - Luis-Eduardo Imbernón Cuadrado; Ángeles Manjarrés Riesco; Félix de la Paz López (From Bioinspired Systems and Biomedical Applications to Machine Learning: 8th International Work-Conference on the Interplay Between Natural and Artificial Computation, IWINAC 2019, Almería, Spain, June 3?7, 2019, Proceedings, Part II, 2019)