Can anyone provide a peer reviewed reference for the calculation of least squares means as implemented in the R package lsmeans? I am using the lsmeans package from the R programming language for follow up analyses of a linear mixed model. However, my target journal does not generally use these methods and I would like to have strong references to back my general approach as well as a general understanding of what is being calculated in the case of a linear mixed model using participants as a random effect. The documentation for the lsmeans package points to a reference page hosted by SAS. Can anyone point me to a peer-reviewed article or book that validates the procedures described there and used by lsmeans for calculating these values? 
Thanks in advance for your assistance. Further thanks to the developers of this great package.
 A: The history of the least squares mean, its appearance in SAS, and its interpretation is discussed in Searle, Milliken, and Speed (1979).
Some discussion of the concepts around least squares means (population marginal means) is found in Searle, Speed, and Milliken (1980).  Earliest mention of the concept that they note is Damon et al (1959).  They provide some other references, but I do not have access to the full article.
The initial implementations of the calculation seem to have been worked out explicitly in Harvey (1960) and some subsequent publications, including but probably not limited to Harvey (1977), Goodnight (1979), Harvey (1982), and Goodnight and Harvey (1997).
It looks like the computation routines were first developed as LSML 76 and LSML GP before the user-contributed PROC HARVEY.
References
J.H. Goodnight (1979) A tutorial on the SWEEP operator.  The American Statistician 33 (3): 149-159.
J.H. Goodnight and W.R. Harvey (1997) Least squares means in the fixed effects general model.  SAS Technical Report R-103.  SAS Institute Inc.
W.R. Harvey (1960) Least-squares analysis of data with unequal subclass numbers.  USDA National Agricultural Library ARS-20-8.
Harvey, W.R (1977) User's guide for LSML 76.  Mixed model least-squares and maximum likelihood computer program.  Ohio State Univ., Colarubus (Mimeo).
W.R. Harvey (1982) Mixed model capabilities of LSML76. Journal of Animal Science 54:1279-1285.
S.R. Searle, F.M. Speed, and G.A. Milliken (1980) Population marginal means in the linear model:  An alternative to least squares means.  The American Statistician 34 (4):216-221.
Searle, S. R., Milliken, G. A., and Speed, F. M. (1979). Expected Marginal Means in the Linear Model. Cornell University Biometrics Unit Technical Reports: Number BU-672-M.
