1. Robert W Levenson . The search for autonomic specificity. The nature of emotion , pages 252 -- 257 , 1994 . Robert W Levenson. The search for autonomic specificity. The nature of emotion, pages 252--257, 1994.
2. Paul Ekman , Wallace V Friesen , and Phoebe Ellsworth . Emotion in the Human Face: Guide-lines for Research and an Integration of Findings: Guidelines for Research and an Integration of Findings . Pergamon , 1972 . Paul Ekman, Wallace V Friesen, and Phoebe Ellsworth. Emotion in the Human Face: Guide-lines for Research and an Integration of Findings: Guidelines for Research and an Integration of Findings. Pergamon, 1972.
3. Differentiating emotion elicited and deliberate emotional facial expressions
4. Paul Ekman and Wallace V Friesen . Unmasking the face: A guide to recognizing emotions from facial clues , volume 10 . Ishk , 2003 . Paul Ekman and Wallace V Friesen. Unmasking the face: A guide to recognizing emotions from facial clues, volume 10. Ishk, 2003.
5. Lie Catching and Microexpressions