The standard for computational grammars and parsers in natural language processing is: Prolog and Natural-Language Analysis - Fernando C. N. Pereira and Stuart M. Shieber The PDF is available from the publisher: http://www.mtome.com/Publications/PNLA/prolog-digital.pdf It also serves as a great introduction to Prolog and logics programming.
I've heard "The Art of Prolog" is good, too... a quick glance at Amazon shows it to be ridiculously expensive, though.
http://www.amazon.com/gp/offer-listing/0262192500/ref=tmm_hr...
...I got mine for like $2, and I've been very happy with it.