Please cite the multcomp package by the following reference:
Hothorn T, Bretz F, Westfall P (2008).“Simultaneous Inference in General Parametric Models.”Biometrical Journal,50(3), 346–363.
Corresponding BibTeX entry:
@Article{, title = {Simultaneous Inference in General Parametric Models}, author = {Torsten Hothorn and Frank Bretz and Peter Westfall}, journal = {Biometrical Journal}, year = {2008}, volume = {50}, number = {3}, pages = {346--363}, }