Roberts B, Harris MG, Yates TA. (2005). "The roles of inducer size and distance in the Ebbinghaus illusion (Titchener circles)". Perception. 34 (7). ss. 847-56. doi:10.1068/p5273. PMID16124270.KB1 bakım: Birden fazla ad: yazar listesi (link)
Roberts B, Harris MG, Yates TA. (2005). "The roles of inducer size and distance in the Ebbinghaus illusion (Titchener circles)". Perception. 34 (7). ss. 847-56. doi:10.1068/p5273. PMID16124270.KB1 bakım: Birden fazla ad: yazar listesi (link)