Ekman, P., & Friesen, W. V. (2003). Unmasking the face: A guide to recognizing emotions from facial clues / Paul Ekman and Wallace V. Friesen (4. [print.].). Malor Books.

Ekman, Paul, and Wallace V. Friesen. Unmasking the Face: A Guide to Recognizing Emotions from Facial Clues / Paul Ekman and Wallace V. Friesen. 4. [print.]. Cambridge, MA: Malor Books, 2003.

Ekman, Paul, and Wallace V. Friesen. Unmasking the Face: A Guide to Recognizing Emotions from Facial Clues / Paul Ekman and Wallace V. Friesen. 4. [print.]. Malor Books, 2003.