Aznar Casanova, J. Antonio, Elton H. Matsushima, Nilton P. Ribeiro Filho, and José A. Da Silva. “One-Dimensional and Multi-Dimensional Studies of the Exocentric Distance Estimates in Frontoparallel Plane, Virtual Space, and Outdoor Open Field”. The Spanish Journal of Psychology, vol. 9, vol. 9, no. 2, 2006, pp. 273-84, https://revistas.ucm.es/index.php/SJOP/article/view/SJOP0606220273A.