Posterior inference on the degrees of freedom parameter in multivariate-t regression models / by Siddharta Chib, Jacek Osiewalski and Mark SteelRegression models under competing covariance matrices: a Bayesian perspective / by Siddhartha Chib, Jacek Osiewalski and Mark SteelA Bayesian note on competing correlation structures in the dynamic linear regression model / Siddharta Chib, Jacek Osiewalski and Mark F.J. Steel