Richard L. Welsh, Bruce B. Blasch, online Foundations of Orientation and Mobility 14 Mart 2020 tarihinde Wayback Machine sitesinde arşivlendi., American Foundation for the Blind, 1997; which cites S. O. Myers and C. G. E. G. Jones, "Obstable experiments: second report", Teacher for the Blind 46, 47–62, 1958.
Rosenblum LD, Gordon MS, Jarquin L. (2000). "Echolocating distance by moving and stationary listeners". Ecol. Psychol. 12 (3). ss. 181-206. doi:10.1207/S15326969ECO1203_1.KB1 bakım: Birden fazla ad: yazar listesi (link)
Richard L. Welsh, Bruce B. Blasch, online Foundations of Orientation and Mobility 14 Mart 2020 tarihinde Wayback Machine sitesinde arşivlendi., American Foundation for the Blind, 1997; which cites S. O. Myers and C. G. E. G. Jones, "Obstable experiments: second report", Teacher for the Blind 46, 47–62, 1958.