Artigo de Ernest Haggard e Keneth Isaacs:
Haggard, E. A., & Isaacs, K. S. (1966). Micro-momentary facial expressions as indicators of ego mechanisms in psychotherapy. In L. A. Gottschalk & A. H. Auerbach (Eds.), Methods of Research in Psychotherapy (pp. 154-165). New York: Appleton-Century-Crofts. Doi: 10.1007/978-1-4684-6045-2_14
Artigo de Paul Ekman e Wallace Friesen:
Ekman, P., & Friesen, W. V. (1969). The repertoire of nonverbal behavior: Categories, origins, usage, and coding. Semiotica, 1(1), 49–98. Doi: 10.1515/semi.1969.1.1.49
