Del Giudice M, Colle L (May 2007). "Differences between children and adults in the recognition of enjoyment smiles". Developmental Psychology. 43 (3): 796–803. doi:10.1037/0012-1649.43.3.796. PMID17484588.
Waller BM, Lembeck M, Kuchenbuch P, Burrows AM, Liebal K (2012). "GibbonFACS: A Muscle-Based Facial Movement Coding System for Hylobatids". International Journal of Primatology. 33 (4): 809–821. doi:10.1007/s10764-012-9611-6. S2CID18321096.
Gudi, Amogh; Tasli, H. Emrah; Den Uyl, Tim M.; Maroulis, Andreas (2015). "Deep learning based FACS Action Unit occurrence and intensity estimation". 2015 11th IEEE International Conference and Workshops on Automatic Face and Gesture Recognition (FG). pp. 1–5. doi:10.1109/FG.2015.7284873. ISBN978-1-4799-6026-2. S2CID6283665.
Del Giudice M, Colle L (May 2007). "Differences between children and adults in the recognition of enjoyment smiles". Developmental Psychology. 43 (3): 796–803. doi:10.1037/0012-1649.43.3.796. PMID17484588.
Waller BM, Lembeck M, Kuchenbuch P, Burrows AM, Liebal K (2012). "GibbonFACS: A Muscle-Based Facial Movement Coding System for Hylobatids". International Journal of Primatology. 33 (4): 809–821. doi:10.1007/s10764-012-9611-6. S2CID18321096.
Gudi, Amogh; Tasli, H. Emrah; Den Uyl, Tim M.; Maroulis, Andreas (2015). "Deep learning based FACS Action Unit occurrence and intensity estimation". 2015 11th IEEE International Conference and Workshops on Automatic Face and Gesture Recognition (FG). pp. 1–5. doi:10.1109/FG.2015.7284873. ISBN978-1-4799-6026-2. S2CID6283665.