2Esteban,J.& D.Ray.On the Measurement of Polarization[J].Institute for Economic Development Discussion Paper,1991:18.
3lasso & Urrutia A.M.An alternativ Formulation of the Esteban-Gradin-Ray Extended Measure of Polarization[J].Journal of Income Distribution,2006(15):42-54.
4Wang Y.Q.& Tsui K.Y.Polarization Ordering and New Class of Polarization Indices[J].Journal of Public Economic Theory,2000(3):349-363.