V. García-hoz, “Signalization and Stimulus-Substitution in Pavlov’s Theory of Conditioning”, Span. j. psychol., vol. 6, no. 2, pp. 168–176, Jan. 2003, Accessed: Nov. 18, 2024. Available: https://revistas.ucm.es/index.php/SJOP/article/view/SJOP0303220168A