См., например, Fasel, B., and Juergen Luettin, “Automatic Facial Expression Analysis: A Survey”, Pattern Recognition 36, no. 1 (January 2003), pp. 259–275, http://www.sciencedirect.com/science/article/pii/S0031320302000523; and Bartlett, Marian Stewart, Gwen Littlewort-Ford, Javier Movellan, Ian Fasel, and Mark Frank, “Automated Facial Action Coding System”, US Patent no. US8798374 B2, August 26, 2009, https://www.google.com/patents/US8798374.
