Newman D. (1939). “The Distribution of Range in Samples from a Normal Population Expressed in Terms of an Independent Estimate of Standard Deviation”. Biometrika31 (1–2): 20–30. doi:10.1093/biomet/31.1-2.20.
Keuls M. (1952). “The Use of the "Studentized Range" in Connection with an Analysis of Variance”. Euphytica1 (2): 112–122. doi:10.1007/bf01908269.