docs: @Reference(authors = "D. J. Best, D. E. Roberts", //
        title = "Algorithm AS 91: The percentage points of the χ² distribution", //
        booktitle = "Journal of the Royal Statistical Society. Series C (Applied Statistics)", //
        url = "https://doi.org/10.2307/2347113", //
        bibkey = "doi:10.2307/2347113")
    public static double quantile(double x, double dof) {
      return GammaDistribution.quantile(x, .5 * dof, .5);
    }