Dervinis, D., G. Daunys, and N. Ramanauskas. “3D Head Orientation Estimation and Expression Influence Minimization Using Characteristic Points of Face”. Elektronika Ir Elektrotechnika, vol. 86, no. 6, July 2008, pp. 47-50, https://eejournal.ktu.lt/index.php/elt/article/view/11182.