Studying the Synoptic Gospels
by Margaret Davies, E. P. Sanders

Synopsis of the Four Gospels : Completely Revised on the Basis of the Greek Text of the Nestle Aland (English-only text)
by Kurt Aland (Editor)

The Five Gospels : What Did Jesus Really Say? The Search for the Authentic Words of Jesus
by Robert W. Funk (Author)

The Case Against Q: Studies in Markan Priority and Synoptic Problem
by Mark Goodacre

Excavating Q: The History and Setting of the Sayings Gospel
by John S. Kloppenborg, John S. Kloppenborg Verbin, Michael Andreas (Preface), Stefan John (Preface)

Ancient Christian Gospels: Their History and Development
by Helmut Koester

M.P. Oakes, "
Statistics for Corpus Linguistics" (Edinburgh: Edinburgh University Press, 1998)
See sections 5.2.5 for "distinctiveness ratios", and for work with a Poisson distribution and a likelihood ratio test

Econometric Analysis", by William H. Greene, (Prentice Hall, 2002)
An article in Science News about related techniques.