Classifying Facial Action. - Marian Stewart Bartlett; Paul A. Viola; Terrence J. Sejnowski; Beatrice A. Golomb; Jan Larsen; Joseph C. Hager; Paul Ekman (NIPS, 1995)

Image Representations for Facial Expression Coding. - Marian Stewart Bartlett; Gianluca Donato; Javier R. Movellan; Joseph C. Hager; Paul Ekman; Terrence J. Sejnowski (NIPS, 1999)

Classifying Facial Actions. - Gianluca Donato; Marian Stewart Bartlett; Joseph C. Hager; Paul Ekman; Terrence J. Sejnowski (IEEE Trans. Pattern Anal. Mach. Intell., 1999)

Individual Differences in Facial Expression: Stability over Time, Relation to Self-Reported Emotion, and Ability to Inform Person Identification. - Jeffrey F. Cohn; Karen L. Schmidt; Ralph Gross; Paul Ekman (ICMI, 2002)

Facial expression analysis. - David Matsumoto; Paul Ekman (Scholarpedia, 2008)