Karl Pearson (1895). "Contributions to the Mathematical Theory of Evolution. II. Skew Variation in Homogeneous Material". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences186: 343–414. doi:10.1098/rsta.1895.0010. Bibcode: 1895RSPTA.186..343P.
harvard.edu
adsabs.harvard.edu
Karl Pearson (1895). "Contributions to the Mathematical Theory of Evolution. II. Skew Variation in Homogeneous Material". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences186: 343–414. doi:10.1098/rsta.1895.0010. Bibcode: 1895RSPTA.186..343P.