To cite lme4, use the following 2 references:
Jeroen C.L. Ooms (2009). yeroon.net/lme4: A web interface for the R package lme4.
Version 0.1. http://www.yeroon.net/lme4
Douglas Bates and Martin Maechler (2009). lme4: Linear mixed-effects models using S4 classes.
R package version 0.999375-31. http://CRAN.Rproject.org/package=lme4
A BibTeX entry for LaTeX users is
@Manual{,
title = {yeroon.net/lme4: A web interface for the R package lme4},
author = {Jeroen C.L. Ooms},
year = {2009},
note = {Version 0.1},
url = {http://www.yeroon.net/lme4},
}
@Manual{,
title = {lme4: Linear mixed-effects models using S4 classes},
author = {Douglas Bates and Martin Maechler},
year = {2009},
note = {R package version 0.999375-31},
url = {http://CRAN.R-project.org/package=lme4},
}