References

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Littell, R. C.,Milliken, G. A.,Stroup, W. W., and Wolfinger, R. D. (1996), SAS System for Mixed Models, Cary, NC: SAS Institute Inc.

Littell, R. C.,Freund, R. J., and Spector, P. C. (1991), SAS System for Linear Models, Third Edition, Cary, NC: SAS Institute Inc.

SAS Institute Inc. (2000), SAS/STAT User's Guide, Version 8, Cary, NC: SAS Institute Inc.

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