On the realization of chiral four-dimensional gauge theories using   branes
  We consider a general brane construction for realizing chiral four-dimensional gauge theories. The advantage of the construction is the simplicity and the possibility of realizing a large class of models existing in the literature. We start the study of these models by determining the matter content and the superpotential which naturally arise in the brane construction. 
A. Hanany and A. Zaffaroni