The Covariant Quantum Superstring and Superparticle from their Classical   Actions
  We develop an approach based on the Noether method to construct nilpotent BRST charges and BRST-invariant actions. We apply this approach first to the holomorphic part of the flat-space covariant superstring, and we find that the ghosts b, c_z which we introduced by hand in our earlier work, are needed to fix gauge symmetries of the ghost action. Then we apply this technique to the superparticle and determine its cohomology. Finally, we extend our results to the combined left- and right-moving sectors of the superstring. 
P.A. Grassi (YITP, Stony Brook), G. Policastro (Scuola Normale Pisa   and NYU), and P. van Nieuwenhuizen (YITP, Stony Brook)