Many people in computational linguistics seem to mention the unexpected power of trigram (or 2nd order Markov) models for language modeling. For instance, it has been stated (verbally) to me on several occasions that trigram models outperform PCFGs.
What would be a good source to cite for trigram models being something of a standard?
What would be a good source to cite for the claim that trigram models outperform more complex models such as PCFGs?
I've gone ahead and started a bounty for this question: even just one good reference will help!