@article {Crai:Rupp:rest:2004, title = {Restricted Likelihood Ratio Tests in Nonparametric Longitudinal Models}, journal = {Statistica Sinica}, volume = {14}, number = {3}, year = {2004}, pages = {713{\textendash}729}, keywords = {Bootstrap, linear mixed models, non-standard asymptotics, penalized splines, subject-specific curves, Variance components}, author = {Crainiceanu, C and Ruppert, D.} }