@article {HockingGreif2012,
    AUTHOR  = {Hocking, Robert and Greif, Chen},
    TITLE   = {Closed-Form Multigrid Smoothing Factors for 
		Lexicographic Gauss-Seidel},
    JOURNAL = {IMA J. Numer. Anal.},
    VOLUME  = 32,
    NUMBER  = 3,
    PAGES   = "795--812",
    YEAR    = {2012}
}