Lenth’s Method for the Analysis of Unreplicated Experiments

http://onlinelibrary.wiley.com/doi/10.1002/9780470061572.eqr014/pdf

http://www.wiley.com/legacy/wileychi/eqr/docs/sample_1.pdf


Box, G. E. P. and Meyer, R. D. (1986).  An analysis for unreplicated fractional factorials.
Technometrics 28 , 11-18.

http://cqpi.engr.wisc.edu/system/files/r002.pdf