References
- Bessel , F.W. 1938 . Untersuchungen Ober die Wahrschelnllchkeit der Beobachtungsfehler . Aatr.Naehr , 15 : 369 – 404 .
- Johnson , N.L. 1949 . Systems of frequency curves generated by methods of translation . Biometrika , 52 : 547 – 58 .
- Pearson , K. 1895 . Contributions to the mathematical theory of evolution. II. Skew variation in homogeneous material . Phil.Trans.Roy.Soc, London A , 186 : 343 – 414 .