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Closer estimators of a common mean in the sense of Pitman
Kubokawa, Tatsuya, (1989)
Double Shrinkage Estimation of Common Coefficients in Two Regression Equations with Heteroscedasticity
Kubokawa, Tatsuya, (1997)
"Estimation of Several Wishart Mean Matrices"
Tsai, Ming-Tien, (2005)