1. Bethscheider, J. K. (1990). The color discrimination project (Technical Report 1990-2). Chicago: Johnson O'Connor Research Foundation.
2. The inertia of the eye and brain;Cattell;Brain,1886
3. Cattell, J. M. (1886). The time taken up by cerebral operations. Mind 11, 220–242, 377–392, 524–538.
4. Daniel, M. H. (1980). Reliability of Pitch Discrimination, Wks. 315 FA (Statistical Bulletin 1980-15). Boston: Johnson O'Connor Research Foundation.
5. Daniel, M. H. (1982). A factorial study of reasoning tests (Technical Report 1982-6). Boston: Johnson O'Connor Research Foundation. (ERIC Document Reproduction Service No. ED 230 571)