Cochran, W.G. (1941) The distribution of the largest of a set of estimated
variances as a fraction of their total. Ann. Eugen. 11, 47--52.
Wilrich, P.-T. (2011) Critical values of Mandel's h and k,
Grubbs and the Cochran test statistic. Adv. Stat. Anal..
tools:::Rd_expr_doi("10.1007/s10182-011-0185-y").