References

Belsley, D. A., Kuh, E., and Welsch, R. E. (1980), Regression Diagnostics , New York: John Wiley & Sons. 

Rawlings, J. O., Pantula, S. G., and Dickey, D. A. (1998), Applied Regression Analysis: A Research Tool , Springer Texts in Statistics, Second Edition, New York: Springer-Verlag. 

Sall, J. (1990), "Leverage Plots for General Linear Hypotheses," The American Statistician , 44(4), 308--315.