Spiegel, R., S. Naqvi, J. Ohene-Djan, D. R. Moore, and E. Hsiao. “A Neuropsychological Perspective on Measuring Sign Language Learning and Comprehension”. International Journal of Emerging Technologies in Learning (iJET), vol. 2, no. 1, Jan. 2007, doi:10.3991/ijet.v2i1.79.