Pinheiro, J. C. and Bates, D. M. (2000), Mixed-Effects Models in S
and S-PLUS, Springer, New York. (Appendix A.21) Venables, W. N. and Ripley, B. D. (1999) Modern Applied
Statistics with S-PLUS (3rd ed), Springer, New York.
Ludbrook, J. (1994), Repeated measurements and multiple comparisons
in cardiovascular research, Cardiovascular Research,
28, 303-311.