1. Churcher, B. G., King, A. J., and Davies, H., The minimum perceptible change of intensity of a pure tone, Phil. Mag., 1934, 18, 7th series, 927–939.
2. Crozier, W. J., On the sensory discrimination of intensities, Proc. Nat. Acad. Sci., 1936, 22, 412–416.
3. Crozier, W. J., and Holway, A. H., On the law for minimal discrimination of intensities, I, Proc. Nat. Acad. Sci., 1937, 23, 23–28.
4. Von Frey, M., Die Tangoreception des Menschen, Hdbk. d. Norm. u. Pathol. Physiol., 1926, Bd. XI (I), 94–100.
5. Von Frey, M., and Kiesow, F., Ueber die Function der Tastkörperchen, Ztschr, f. Psychol u. Physiol der Sinnesorg., 1899, 20, 126–163.