Gu, C. and Wahba, G. (1993a). Smoothing Spline ANOVA with component-wise Bayesian confidence intervals.
Journal of Computational and Graphical Statistics 55, 353--368.
Gu, C. and Wahba, G. (1993b). Semiparametric analysis of variance with tensor product thin plate
splines. JRSS B 55, 353--368.