1. Erdelyi, A. et. al. Ed.: Tables of integral transforms, Volume I, McGraw-Hill, New York. (1954).
2. Ray, W. D. andPitman, A. E.N.T.: An exact distribution of the Fisher-Behren’s-Welch statistic for testing the difference between the means of two normal populations with unknown variances. J. Roy. Statist. Soc. B23, 377 (1961).
3. Ruben H.: On the distribution of the weighted difference of two independent student variables. J. Roy. Statist. Soc. B22, 188 (1960).