P. S. D. Soares Filho, Álvaro J. M. Silva, S. M. Velasco, R. S. Barros, and G. Y. Tomanari, “Assessing Symmetry by Comparing the Acquisition of Symmetric and Nonsymmetric Conditional Relations in a Capuchin Monkey”, Int. j. psychol. res., vol. 9, no. 2, pp. 30–39, Jul. 2016.