Oral Tradition and Literary Dependency
A book which looks worthy of a look is that by Terence C. Mournet, Oral Tradition and Literary Dependency: Variability and Stability in the Synoptic Tradition and Q (Tübingen: Mohr Siebeck, 2005). It is Mournet's revised doctoral thesis supervised by James D. G. Dunn so it may also help shed some light on Dunn's unclear perspective concerning what counts as oral sources in Mt & Lk (Mournet, like Dunn, presupposes some form of the Mk-Q hypothesis). When I get hold of a copy I hope to comment on it here.